/*
 * Reader stylesheet.
 *
 * This file is the single most product-defining piece of CSS in the project, so
 * its rules are stated explicitly rather than arrived at by accident.
 *
 * THE STRATEGY: preserve the author's design, override almost nothing.
 *
 * The reason this product exists (product design §9) is that every other
 * self-hosted library renders books at "web reader" quality, and the reason the
 * obvious solution is wrong (§5, decision 2) is that Readium CSS takes over the
 * book's typography to make every book look the same. That is a reasonable
 * trade for a generic reader and the exact opposite of this product's promise to
 * faithfully reproduce a carefully typeset book.
 *
 * So the rules here follow three principles:
 *
 *   1. No property is set unless something actually breaks without it.
 *   2. Every adjustable property is an inheriting custom property whose default
 *      is the author's value, so "off" means "untouched", not "our default".
 *   3. Anything that changes the author's intent is a user opt-in that persists,
 *      never a default.
 *
 * The comments call out each rule that *does* override, and why it has to.
 */

/* ------------------------------------------------------------------ *
 * Host shell: the viewer, not the book. Safe to style freely.
 * ------------------------------------------------------------------ */

:root {
  --reader-ink: #1a1a1a;
  --reader-paper: #fbfaf7;
  --reader-surface: #ffffff;
  --reader-muted: #6b6b6b;
  --reader-line: #e3e0da;
  --reader-accent: #7a5c3e;
  --reader-radius: 10px;
  --collection-measure: 80rem;

  /*
   * How far a search field is inset inside its content column, on *both* sides.
   *
   * One token rather than two margins, because the two have to be equal for the field
   * to stay centred — and it is declared here rather than on `.shelf` because the
   * *library* has the same field and it is not inside a shelf: a token that lives on
   * one screen's element and is read by another screen's rule resolves to nothing, and
   * `padding-inline: var(--undefined)` is `padding-inline: 0` — i.e. the gutters this
   * token exists to create silently do not appear, which is exactly how it shipped for
   * one round of this review.
   */
  --shelf-search-inset: 0.75rem;

  /*
   * The spacing scale.
   *
   * Four steps, not eight. A larger scale reads as precision and behaves as a
   * suggestion: once `1.75rem` and `2rem` both exist, half the stylesheet uses one
   * and half the other and the inconsistency is invisible in any single rule.
   *
   * The values are the ones the stylesheet already used, promoted to names so that
   * "put this a bit further from that" becomes "which step is this" — the question
   * that actually has an answer.
   */
  --space-1: 0.35rem; /* inline gaps inside a control */
  --space-2: 0.6rem;  /* padding inside a control */
  --space-3: 0.9rem;  /* gutter between sections */
  --space-4: 1.5rem;  /* padding inside a page-level band */

  /*
   * The type scale. Named by role rather than by size, because the size is the part
   * that changes and the role is the part that does not: `--text-meta` is "the line
   * under a title" whether it is 0.72rem today or 0.75rem later.
   */
  --text-title: 1.05rem;
  --text-body: 0.95rem;
  --text-label: 0.82rem;
  --text-meta: 0.72rem;

  /*
   * Motion.
   *
   * One duration and one easing for everything, so a panel, a toast and a scrim
   * move together. Two durations in a UI is the same mistake as two radii: each is
   * defensible alone and the pair is visibly wrong.
   *
   * A `prefers-reduced-motion` block at the end of this file collapses every
   * duration to a hair, including these, so honouring the preference is one rule
   * rather than an audit of every transition.
   */
  --motion-duration: 0.18s;
  --motion-ease: cubic-bezier(0.32, 0.72, 0, 1);

  /*
   * The focus ring.
   *
   * Defined as a token because it has to be drawn in three situations — on the
   * paper, on a surface, and over a book's page — and the colour that reads against
   * one does not read against the others. `currentColor` does not work here: the
   * ring must stay visible when the control's own colour is the background.
   */
  --focus-ring: 2px solid color-mix(in srgb, var(--reader-accent) 70%, transparent);
  --focus-offset: 2px;

  /*
   * The insets every full-bleed band respects.
   *
   * Defined here, in one place, and *not* read straight from `env()` at each use
   * site. Two reasons, and the second one is the whole point of the indirection:
   * one name per edge means the phone, the browser and the Android shell cannot
   * each end up with a slightly different idea of where the screen starts; and
   * an undefined custom property makes the whole `calc()` invalid, which drops
   * the declaration silently. A `padding: calc(0.9rem + var(--safe-left))` on an
   * element whose variable is unset is not "0.9rem of padding" — it is *no
   * padding at all*, and the fingerprint was a header with zero left inset while
   * the rule that set it looked correct.
   */
  --safe-top: env(safe-area-inset-top, 0px);
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  --safe-left: env(safe-area-inset-left, 0px);
  --safe-right: env(safe-area-inset-right, 0px);

  /*
   * The three user controls, in their default = do-not-touch position.
   *
   * `inherit` rather than a concrete value is deliberate for line-height and
   * font-size: the author set them on `body` or on a specific paragraph, and an
   * explicit value here would flatten a book that varies them by section. When
   * the reader picks a size in the UI, JS writes a concrete value.
   */
  --reader-font-scale: 1;
  --reader-line-height: inherit;
  --reader-font-family: inherit;
  --reader-text-align: inherit;
  --reader-page-margin: 1.5rem;
  --reader-brightness: 1;
  --reader-measure: 42rem;

  --reader-page-padding-inline: 1.5rem;
  --reader-page-padding-block: 1.25rem;

  /*
   * The inset every *band* — the top bar's row of buttons, the footer's two rows,
   * the reading indicator's two readouts — is drawn to.
   *
   * Declared once because the three of them sit at the two edges of the same page
   * and the reader reads their edges as one line. They were separate numbers
   * before: the top bar had 0.35rem of padding, the scrubber row 0.75rem and the
   * chapter row 0.75rem, so nothing lined up with anything and the mismatch read
   * as three unrelated bars rather than one frame around the text. The two
   * readouts at the bottom (page count and chapter navigation) are the pair the
   * reader looks at together, and they were 0.4rem apart from each other.
   *
   * `0.75rem` rather than the page's own 1.5rem margin: a band is chrome, and the
   * controls inside it are what the reader aims at, so its inset is the gap
   * between the outermost control and the device edge rather than the measure the
   * book is set to.
   */
  --reader-band-inset: 0.75rem;

  /*
   * The surface a floating band is drawn on.
   *
   * Translucent, with a blur, and that is what makes a bar over the text usable
   * now that the page is not inset for it: the reader can see the line the bar
   * covers *through* the bar, so the toolbar stops being a thing that hides a
   * paragraph. `color-mix` against the theme's own surface rather than a fixed
   * rgba, so the three themes get their own tint from one value; the fallback is
   * the opaque surface, which is what a host without `color-mix` draws and which
   * is exactly the old behaviour.
   */
  --reader-surface-float: color-mix(in srgb, var(--reader-surface) 88%, transparent);

  /*
   * The reader's own paint order, weakest first.
   *
   * The three numbers exist because the reading surface and the chrome are
   * *positioned siblings*, and positioned siblings with no `z-index` are painted in
   * document order — which is how the chapter's own text came to be drawn over the
   * chapter name in immersion. The immersion readouts in particular have to be above
   * the page, because the whole point of them is that the reader can still see where
   * they are; the page cannot be above the thing that describes it. Declared as a
   * named scale rather than as three literals so the relationship is readable and a
   * fourth band has an obvious place to go.
   */
  --reader-layer-page: 1;     /* the reading surface: below everything else here */
  --reader-layer-bar: 10;     /* the two floating bars, over the page */
  --reader-layer-rail: 14;    /* the quick-action column */
  --reader-layer-panel: 20;   /* sheets and their scrim */
  --reader-layer-readout: 5;  /* above the page, below bars and sheets */

  /*
   * The reading indicator's own inset.
   *
   * Wider than a band's, because the indicator is not chrome: it is text, drawn
   * over the page while the reader is reading, so it is set to the *page margin* —
   * the same measure the book is typeset to, which is what makes it look like a
   * caption on the page rather than a label stuck to the screen. `--reader-page-margin`
   * is the reader's own control (0 by default would be flush with the band, 4rem
   * would be a well-inset caption) and `--reader-page-padding-inline` is the floor,
   * so the readouts never overlap the paragraph underneath on a device where the
   * margin is set to nothing.
   */
  --reader-indicator-inset: max(
    var(--reader-page-margin),
    var(--reader-page-padding-inline)
  );
}

[data-theme='sepia'] {
  --reader-ink: #3b3327;
  --reader-paper: #f5ecd9;
  --reader-surface: #f9f3e4;
  --reader-line: #e0d3ba;
}

[data-theme='dark'] {
  --reader-ink: #d8d4cc;
  --reader-paper: #16171a;
  --reader-surface: #1e2024;
  --reader-muted: #9a958c;
  --reader-line: #33363b;
  --reader-accent: #b39272;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  background: var(--reader-paper);
  color: var(--reader-ink);
  font-family: system-ui, -apple-system, 'Segoe UI', 'Noto Sans SC', sans-serif;
  -webkit-text-size-adjust: 100%;
  overscroll-behavior: none;
}

#app {
  display: flex;
  flex-direction: column;
  height: 100%;
  /*
   * The reader is an app, not a document: a rubber-band overscroll on Android
   * shows a white flash behind the paper colour, and a pull-to-refresh gesture
   * at the top of a chapter reloads the whole SPA.
   */
  overflow: hidden;
}

/* ------------------------------------------------------------------ *
 * The book stage
 * ------------------------------------------------------------------ */

.stage {
  position: relative;
  flex: 1 1 auto;
  min-height: 0;
  background: var(--reader-paper);
  overflow: hidden;
}

/*
 * The stage's slot in the component tree.
 *
 * A wrapper rather than the stage itself, because the stage is owned by the
 * screen and handed in through a ref callback (see `StageHost`): it is a node
 * with its own lifetime, and putting it in a tree that re-renders is how a
 * chapter's shadow root ends up detached from the element the paginator
 * measured.
 *
 * Pinned to the *screen* rather than to whatever the flex column had left over,
 * and that is the whole of the "内容会上下滑动" fix: with the stage in flow, the
 * two bars took height out of it, so showing or hiding the chrome resized the page
 * and moved every line on it. Here the page is the screen, always, in both states.
 *
 * ## No block inset: the page *is* the screen
 * —
 * This rule used to reserve the bars' own heights as `padding-block`, on the
 * reasoning that a floating bar must not cover a line the reader is reading. The
 * reasoning was sound and the result was the report: "内容要铺满，不要预留 stage".
 * Reserving the bars' height means the reading column is permanently 9rem shorter
 * than the phone, in *both* chrome states — so a reader who has hidden the toolbar
 * and wants the whole screen for the book still loses the top and bottom bands to
 * empty paper, and the last line of every page sits 5.6rem above the bottom edge
 * for no reason at all.
 *
 * The column keeps its own `padding-block` (see `FLOW_STYLESHEET`), which is the
 * reader's *page* padding and is symmetric — the text is not flush with the glass
 * even when the bars are gone. What it is not is a variable reserve for chrome
 * that may not be there: the page occupies the whole slot and the bars are drawn
 * over it, which is what "浮动" means and what makes the text stand still when
 * they come and go.
 */
.stage-host {
  display: flex;
  position: absolute;
  inset: 0;
}

/*
 * The stage fills its slot.
 *
 * `.stage` is `position: relative` with a percentage-free height, which is all it
 * needs once its parent is a flex container — but the parent is `.stage-host`
 * above, added when the chrome became a component tree, and a *block* parent
 * gives an auto-height child its content height instead of the slot's. The stage
 * then measures zero and the book is laid out in a band at the top of the
 * screen. `flex: 1` here is what restores "the stage is the space between the
 * chrome", which is the one thing this layout is supposed to guarantee.
 */
.stage-host > .stage {
  flex: 1 1 auto;
  min-height: 0;
}

/*
 * The chapter document is rendered into a shadow root so a book's own
 * stylesheet cannot reach the app chrome, and the app chrome cannot reach into
 * the book. The two only meet through the custom properties above.
 */
/*
 * The reading surface, and its place in the paint order.
 *
 * It is `position: absolute` inside `.stage`, so it is a *positioned* box — and a
 * positioned box with no `z-index` paints in **document order** against its
 * positioned siblings. It is appended before the chrome is rendered, so it comes
 * after the immersion readouts, which is how the chapter's own text came to be
 * drawn over the chapter name that describes it. One declared number fixes that,
 * and it is the page's place in the layer scale declared with the other tokens.
 */
.book-host {
  position: absolute;
  inset: 0;
  overflow: hidden;
  z-index: var(--reader-layer-page);
}

.book-host[data-layout='reflowable'] {
  overflow-x: hidden;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

/*
 * Fixed-layout pages are advanced by the pager, not scrolled, so the host must
 * not be a scroll container: a nested scroll area on top of a horizontal pager
 * produces the classic "the page drifts sideways" bug on Android.
 */
.book-host[data-layout='fixed'] {
  overflow: hidden;
  display: grid;
  place-items: center;
}

/*
 * The reading column's own rules are in `ui/shadow.ts`, not here — and that
 * separation is load-bearing.
 *
 * `.book-flow`, `.fixed-page`, `.reader-speech-highlight` and the page-turn
 * animations all belong to elements inside the book's *shadow root*, and a
 * selector in a document stylesheet does not reach into a shadow root. Declaring
 * them here is therefore indistinguishable from deleting them: the column
 * rendered at the browser default — no measure, no margins, no font scale, and
 * no columns in paged mode — while the surrounding chrome, which *is* in the
 * document, looked perfectly styled. That asymmetry is what made it read as a
 * missing feature rather than a missing stylesheet.
 *
 * What stays below is everything that is genuinely in the document: the
 * brightness overlay (a pseudo-element on the *host*, which is light DOM), the
 * host element's own box, and the chrome.
 */

/*
 * Brightness.
 *
 * A dimming bed-time overlay rather than a change to the palette: the reader's
 * theme is the author's colours, and darkening them keeps the relationship
 * between paper and ink. An overlay *on top* would darken the text as much as
 * the paper, which is what makes a "brightness" slider feel broken. Applied with
 * `mix-blend-mode: multiply` on a pseudo-element so it costs no extra DOM and
 * cannot be reached by the book.
 */
.book-host[data-layout='reflowable']::after {
  content: '';
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 5;
  background: #000;
  opacity: calc(1 - var(--reader-brightness));
  mix-blend-mode: multiply;
}

/*
 * The host is the scroll container in scroll mode and a plain frame in paged
 * mode; `book-content` is an unknown element to the browser, so its `display`
 * has to be stated.
 */
book-content {
  display: block;
}

/* ------------------------------------------------------------------ *
 * Chrome: header, shelf, panels
 * ------------------------------------------------------------------ */

/*
 * Whether the chrome is on screen.
 *
 * The topbar and the footer are one state, not two, and that is the whole of the
 * "沉浸式" request: a reader who hides the navigation wants the page and nothing
 * else, and a header that hides while the footer stays is a footer that keeps
 * covering the last two lines of every page. So both are toggled by one attribute
 * on the screen, both animate with the same duration and easing, and neither can be
 * on screen without the other.
 *
 * Both bars *float*. They are positioned overlays rather than rows in a column, so
 * the page beneath them is the whole screen whichever state they are in — which is
 * the difference between "the toolbar appears" and "the toolbar appears *and* pushes
 * everything the reader was looking at up by 53px". It was the second, and it was
 * reported as such: a tap on the middle third slid the text up and a second tap slid
 * it back down. The reader's own diagnosis was the right one — a toolbar is a
 * floating layer, and a layout that lets it displace content has the chrome and the
 * page in the same flow when they are not.
 *
 * The cost of floating is that the bars cover the top and bottom of the page, so the
 * reading column keeps a constant inset clear of them (`--reader-chrome-inset-*` on
 * the flow, in `ui/shadow.ts`). Constant is the operative word: the inset does not
 * change with the chrome's state, because a page that re-typesets itself when the
 * reader taps is the same defect wearing a different hat.
 */
.reader-screen {
  display: block;
  height: 100%;
  position: relative;
  /*
   * The chrome's own height, in one place.
   *
   * These are *measurements of the bars*, not space the layout reserves. The bars
   * float over the page (see `.topbar`), so the page is the whole screen in both
   * states and the numbers are only what the reading column has to keep clear of.
   *
   * They were previously the stage's own height arithmetic — the bands grew and
   * shrank and the stage, being `flex: 1`, took whatever was left. That is what made
   * a tap on the middle third *move the text*: every time the reader asked for the
   * controls the page re-laid out 3.4rem shorter, and the line they were reading
   * slid up the screen by 53px and back down again when they hid it. On a reader
   * that is the worst possible motion — it is the text moving, and the text is the
   * one thing that must stay still. So the geometry is constant and the bars are
   * drawn over it.
   */
  --reader-chrome-top: 3.4rem;
  --reader-chrome-bottom: 5.6rem;
}

.topbar {
  display: flex;
  /*
   * Over the page, not above it. `position: absolute` is what makes the bars a
   * layer rather than a row: with them in flow, the stage was `flex: 1` of what was
   * left, so the page grew and shrank by the bars' height on every toggle and every
   * line of the chapter moved with it.
   */
  position: absolute;
  inset-inline: 0;
  top: 0;
  z-index: var(--reader-layer-bar);
  /*
   * `stretch`, so each button owns the full height of the band. The buttons are
   * icon-over-label now, and a button that only owned its two lines would leave a
   * strip of the bar above and below that looked identical but did nothing — on
   * the one row where the reader is aiming at controls rather than at text.
   */
  align-items: stretch;
  /*
   * Three columns, and the outer two are pinned to their own edges.
   *
   * This is the alignment the reader reads *vertically*: 返回 at the top of the
   * screen and 上一章 at the bottom are the same thing in the reader's head — "the
   * leftmost control" — so their left edges have to be one line. They were not.
   * The bar was `space-evenly` over three equal-width buttons, so 返回's glyph sat
   * 70px in, centred in its own third, while 上一章 began 12px from the device edge.
   * Two rows framing the same text with corners that do not meet read as broken,
   * without the reader being able to name what is wrong.
   *
   * A grid rather than `space-between`, and that distinction is the whole fix:
   * `space-between` distributes *free* space, and with `flex: 1 1 0` buttons there
   * is none — three equal columns fill the row exactly, so the property has nothing
   * to do and the buttons stay centred in their boxes. The grid says what is
   * actually wanted: three tracks, the first item flush start, the last flush end,
   * the middle one centred. Those are the same three positions the footer's two
   * chapter buttons and its progress readout occupy, and they are stated once, on
   * the same `--reader-band-inset` both rows take their padding from.
   */
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  justify-items: center;
  gap: var(--space-1);
  min-height: 3.4rem;
  /* The band inset on both sides, so the outermost glyphs are the same distance
     from the device edge as every control in the footer below them. */
  padding-inline: var(--reader-band-inset);
  /* A floating band over the page, not a solid shelf above it: the reader has to be
     able to read the line it covers. See `--reader-surface-float`. */
  background: var(--reader-surface-float);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  /* Same hairline treatment as the footer, so the two edges of the reading area
     are the same weight. */
  border-bottom: 1px solid color-mix(in srgb, var(--reader-line) 80%, transparent);
  padding-top: var(--safe-top);
  /* The band's own height, which the reading column also reads as the inset it has
     to keep clear of. One number, so the bar and the space reserved for it cannot
     disagree. */
  height: var(--reader-chrome-top);
  /* Nothing is animated but the band's own opacity and position: no layout property
     is touched, which is what makes the motion free of any effect on the page. */
  transition:
    opacity var(--motion-duration) var(--motion-ease),
    transform var(--motion-duration) var(--motion-ease),
    visibility 0s linear var(--motion-duration);
}

/*
 * Hidden: the band slides up out of the way and fades.
 *
 * `visibility` rather than `display: none` so the slide has something to animate,
 * and `visibility: hidden` at the *end* of it so the (invisible) bar cannot be
 * reached by a screen reader or a tap. `pointer-events: none` covers the interval
 * itself, which is the part `visibility` alone does not: a control on its way off
 * the screen is still a control for the duration of the fade.
 *
 * No height is animated, because there is no height to give back — the page never
 * had less of it. That is the point of the bars being a layer.
 */
.reader-screen[data-chrome='hidden'] .topbar {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  border-bottom-color: transparent;
  transform: translateY(-100%);
}

/*
 * One icon-over-label control in the top bar.
 *
 * A column, so the glyph and the word are one hit target rather than two; the word
 * is drawn rather than left to a tooltip because the glyphs here are not universal
 * (a list and a slider read as the same thing without it). The label is the small
 * `--text-meta` size — it is a caption for the glyph, not a second title.
 */
/*
 * One control of the top bar.
 *
 * `flex: 1 1 0` gives all three the same *width*, and that is the whole of how the
 * row comes out symmetric: with three equal columns there is no free space left for
 * `space-evenly` to distribute as gaps, so the two outer buttons start and end
 * exactly on the bar's own inset and the two interior gaps are equal. The reader's
 * "顶部栏三个按钮需要两边对齐" was not achievable while the columns had a
 * `max-width`: the row was `space-evenly` *with* a 6rem cap, so the free space left
 * over grew with the screen and was inserted as *gaps* — which are computed from
 * what is left, and therefore came out unequal for labels of unequal width. The
 * measured result was outer edges 29px in while the footer's were 12px in, on the
 * same screen.
 *
 * The ceiling is gone rather than moved. It read as a sensible tablet refinement
 * ("three 6rem buttons across 800px is a lot of air") and it was precisely what
 * broke the alignment, because a row narrower than its bar always has space to
 * insert somewhere. A row at `100%` has no leftover space at any width, so its
 * edges are the bar's inset everywhere — which is the property that makes the top
 * bar and the footer share one frame. `flex: 1` is already the ceiling; the row
 * cannot exceed the bar.
 *
 * `flex-basis: 0` also means a long label cannot make its own column wider than its
 * neighbours: 返回 and 设置 are the same target whatever the words say.
 */
.top-button {
  min-width: 0;
  max-width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.15rem;
  padding: 0.3rem 0.25rem;
  border: 0;
  border-radius: var(--reader-radius);
  background: transparent;
  color: var(--reader-ink);
  font: inherit;
  font-size: 1.15rem;
  cursor: pointer;
  touch-action: manipulation;
  transition: background var(--motion-duration) var(--motion-ease);
}

/* The outer two flush to the band's own inset, which is where the footer's two
   chapter buttons put their edges — see the grid comment above. The middle button
   stays centred, which is where the reader expects the middle control. */
.topbar > .top-button:first-child {
  justify-self: start;
}

.topbar > .top-button:last-child {
  justify-self: end;
}

.top-button:active {
  background: color-mix(in srgb, var(--reader-ink) 8%, transparent);
}

.top-button-label {
  font-size: var(--text-meta);
  font-weight: 400;
  color: var(--reader-muted);
  line-height: 1;
  white-space: nowrap;
}

/* Shared sizing for the SVG icon primitive. */
.icon {
  font-size: 1.15rem;
  font-style: normal;
  font-weight: 400;
  font-synthesis: none;
  line-height: 1;
  display: inline-block;
  width: 1em;
  text-align: center;
  vertical-align: middle;
  speak: never;
  /* The code point itself must never be selectable or copied. */
  user-select: none;
  -webkit-user-select: none;
}

/*
 * A square control with its glyph centred in it.
 *
 * `inline-grid` rather than `grid`: a `grid` is block-level, so a button in a row of
 * text starts a line of its own and the row it was supposed to sit in grows a
 * baseline that has nothing to do with the text. `vertical-align` is what a control
 * in a text row is aligned with, and it only applies to inline-level boxes.
 *
 * The glyph is centred on the box's *centre* — `place-content`, which is relative to
 * the box — where the old rule used `place-items` on the implicit grid area. The
 * area is the same box, so the pixels are the same pixels on every browser that
 * exists; saying it in terms of the box is what keeps that true when the button grows
 * a border or a padding, because the centre is still the centre.
 *
 * This is also why `.icon` must be a *line box* rather than a 1em square: a grid
 * centres the box it is given, so the ink has to be in the middle of that box for the
 * centring to be visible. See the derivation on `.icon`.
 */
.icon-button {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--reader-ink);
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--reader-radius);
  font-size: 1.1rem;
  display: inline-grid;
  place-content: center;
  vertical-align: middle;
  cursor: pointer;
  touch-action: manipulation;
}

.icon-button:active {
  background: color-mix(in srgb, var(--reader-ink) 10%, transparent);
}

.button {
  appearance: none;
  border: 1px solid var(--reader-line);
  background: var(--reader-surface);
  color: var(--reader-ink);
  border-radius: var(--reader-radius);
  padding: 0.6rem 1rem;
  font-size: 0.95rem;
  cursor: pointer;
  touch-action: manipulation;
}

.button.primary {
  background: var(--reader-accent);
  border-color: var(--reader-accent);
  color: #fff;
}

.button:disabled {
  opacity: 0.55;
  cursor: default;
}

/*
 * A button whose contents are a glyph and a label.
 *
 * The gap is the whole reason this is a rule rather than incidental whitespace: the
 * glyph is one em wide whatever the font-size, so `gap` is the only thing that can
 * keep the space between icon and text equal across buttons at different sizes. The
 * flex line centres both boxes on the button's centre, which is where they have to
 * be, and cannot be written any other way.
 */
.icon-text-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  vertical-align: middle;
  /*
   * The label does not wrap, and the padding is the header's rather than the body's.
   *
   * In a *body* (an empty state, a dialog) a `.button` is a standalone control and the
   * roomy padding is right. In a *header* it sits in a fixed-height row beside a
   * breadcrumb, and the two together decide what the row looks like: a four-character
   * Chinese label at `0.95rem` with `1rem` of padding either side is 90px, which on a
   * 390px screen pushed it onto two lines and made the header taller than the icon
   * buttons beside it. `nowrap` is the second half of the same fix — a label that wraps
   * is the failure this rule exists to prevent, not a way to fit.
   */
  white-space: nowrap;
  flex: 0 0 auto;
}

.panel-header .icon-text-button {
  padding: 0.45rem 0.6rem;
  font-size: 0.82rem;
}

/* ---- interactive states ---- */

/*
 * One focus rule for every control in the product.
 *
 * This block did not exist. The stylesheet had a `:focus-visible` rule on the
 * search field and *nothing* on any button, which meant the only way to see where
 * the keyboard was on a shelf full of controls was to guess. It is written as a
 * single rule over a list of selectors rather than per-component so that a new
 * control inherits the behaviour: adding one to this list is the whole job.
 *
 * `:focus-visible` rather than `:focus` on purpose — a mouse click on a button
 * should not leave a ring behind, and a keyboard tab must always show one.
 */
.button:focus-visible,
.icon-button:focus-visible,
.chip:focus-visible,
.switch:focus-visible,
.segmented button:focus-visible,
.toc-list li button:focus-visible,
.manager-row:focus-visible,
.manager-crumb:focus-visible,
.search-clear:focus-visible,
.tts-bar button:focus-visible,
.pager-page:focus-visible,
.pager-step:focus-visible,
.dialog button:focus-visible {
  outline: var(--focus-ring);
  outline-offset: var(--focus-offset);
}

/*
 * Hover, for the pointer-equipped half of the audience.
 *
 * Guarded by `hover: hover` because on a touch device every tap would otherwise
 * leave the last-tapped control stuck in its hover appearance — the phone shows a
 * control as "hovered" as soon as the finger lifts, which makes the state look
 * broken rather than responsive.
 */
@media (hover: hover) and (pointer: fine) {
  .icon-button:hover,
  .button:hover,
  .chip:hover,
  .manager-row:hover,
  .manager-crumb:hover,
  .search-clear:hover,
  .pager-page:hover,
  .pager-step:hover,
  .toc-list li button:hover {
    background: color-mix(in srgb, var(--reader-ink) 6%, transparent);
  }

  /* Hover must not paint over the one page the reader is *on*: the fill is the
     state, and a hover that replaces it hides exactly the fact the control carries. */
  .pager-page[aria-current='page']:hover {
    background: var(--reader-accent);
  }

  .button.primary:hover {
    background: color-mix(in srgb, var(--reader-accent) 88%, var(--reader-ink));
    border-color: transparent;
  }

  .button.danger:hover {
    background: color-mix(in srgb, #c0392b 10%, var(--reader-surface));
  }
}

/*
 * Every state transition in one place, using one duration and one easing.
 *
 * The individual rules further down used to carry their own `0.15s ease` /
 * `160ms ease-out` / `120ms ease`, which is three answers to a question that has
 * one. A control's feedback should be the same speed as every other control's
 * feedback, or the app feels like it was assembled from several apps.
 */
.button,
.icon-button,
.chip,
.manager-row,
.manager-crumb,
.search-clear,
.pager-page,
.pager-step,
.toc-list li button,
.segmented button {
  transition:
    background-color var(--motion-duration) var(--motion-ease),
    border-color var(--motion-duration) var(--motion-ease),
    color var(--motion-duration) var(--motion-ease),
    opacity var(--motion-duration) var(--motion-ease);
}

/*
 * The controls inside a settings row.
 *
 * Sized to the row rather than to the sheet: a select that spans the whole sheet is
 * a control whose value is far from its label, and a range input that does is a
 * slider the reader has to hunt for the thumb of. The 16px floor is not cosmetic
 * either — anything smaller makes iOS Safari zoom the page on focus, which leaves
 * the layout scrolled and half off-screen with no way back except a pinch.
 */
.field input,
.field select,
.field textarea {
  appearance: none;
  border: 1px solid var(--reader-line);
  background: var(--reader-surface);
  color: var(--reader-ink);
  border-radius: var(--reader-radius);
  padding: 0.45rem 0.6rem;
  font-size: 16px;
  font-family: inherit;
  width: 100%;
}

.field input[type='range'] {
  padding: 0;
  border: 0;
  background: transparent;
  accent-color: var(--reader-accent);
}

/* ---- shelf: the home screen ---- */

/*
 * The shelf is the most-opened screen in the product, and it is also the only one
 * a reader sees before they have decided whether to trust the app. So its layout
 * is stated rather than arrived at, and the three decisions below are the ones
 * the previous version got wrong.
 *
 *  1. **It reads top-down like a page, not like a toolbar.** The old version led
 *     with a search box, then counted books, then offered four sort chips — three
 *     rows of controls before a single cover. A library's first job is to show the
 *     library, so the title and the covers come first and the controls sit *with*
 *     the section they act on.
 *  2. **Nothing is centred.** `.centered-form` and `.empty-state` were `text-align:
 *     center` with `padding: 1.5rem`, which is right for an empty state and wrong
 *     for a shelf of two thousand books. The grid is left-aligned and its own edge
 *     is the alignment.
 *  3. **The header is not sticky, the toolbar is.** A sticky band carrying the
 *     title costs 4rem of a phone's height permanently to say something the reader
 *     already knows. A sticky band carrying the count and the sort control earns
 *     it: those are the two things a reader scrolls back up to change.
 */

.shelf {
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  padding: 0 0 var(--safe-bottom);
  /*
   * On a wide window the shelf is centred and capped rather than stretched.
   *
   * `auto-fill` on a 1600px monitor otherwise produces eleven covers a row, each
   * with a twelve-character title — a wall of thumbnails that is *harder* to scan
   * than a phone's three, which is the opposite of what the extra width is for. A
   * cap also means the search field and the sort chips stop being a metre wide,
   * so the eye does not have to travel the full window to use them.
   *
   * `--shelf-measure` is the maximum content width, not the viewport's: the cover
   * size below is scaled against it, so widening the window past the cap adds
   * margin instead of more columns.
   */
  --shelf-measure: 68rem;
  /*
   * One place sets the gutter. Every band inside the scroller — the header, the
   * search box, the toolbar, the sections — reuses it, so they cannot drift apart
   * and a cover can never sit nearer the screen edge than the title above it.
   */
  --shelf-gutter: 0.9rem;
  --shelf-gutter-end: calc(0.9rem + var(--safe-right));
}

/* ---- header ---- */

.shelf-head {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: calc(0.9rem + var(--safe-top)) calc(0.9rem + var(--safe-left)) 0.5rem
    var(--shelf-gutter-end);
  max-width: var(--shelf-measure);
  margin-inline: auto;
}

.shelf-head-text {
  flex: 1 1 auto;
  min-width: 0;
}

/*
 * The title block.
 *
 * One screen title, its count beneath it, and two actions on the right — which is
 * what the reference稿 shows and what the previous arrangement did not. The count was
 * a separate row *below* the search field, so the same fact ("共 12 本") appeared two
 * rows away from the thing it counts and had to be re-found after every search.
 */
.shelf-title {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 650;
  letter-spacing: -0.02em;
  line-height: 1.15;
  /* The title is the one piece of text on this screen at a display size, so it gets
     the optical correction the smaller sizes do not need: `-0.02em` closes the gaps
     that a large weight opens between Chinese glyphs and Latin capitals alike. */
}

.shelf-subtitle {
  margin: 0.25rem 0 0;
  font-size: 0.76rem;
  line-height: 1.35;
}

.shelf-head-actions {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  flex: 0 0 auto;
  /* Nudged back up so the 40px target of the first button aligns with the cap
     height of the title rather than with its baseline. */
  margin-top: -0.45rem;
}

/* ---- search ---- */

/*
 * The field is a pill with the glyph inside it, and it is exactly as wide as the
 * content column. `font-size: 16px` is not a taste decision — anything smaller
 * makes iOS Safari zoom the viewport on focus and leave the layout half
 * off-screen, which on a *search field* means the shelf jumps every time it is
 * used.
 */
.shelf-search {
  /*
   * `position: relative` and a *centre*-aligned row: both the magnifier and the
   * clear button are absolutely positioned against this box, and absolute
   * positioning resolves against the padding box' top edge, so a row aligned any
   * other way would put the glyph where the *field* is not.
   */
  position: relative;
  display: flex;
  align-items: center;
  /*
   * The field is inset from the covers above and below it, on both sides.
   *
   * This was reported as 「书架的搜索框两边需要增加 margin」 and it is a *gutter*
   * problem rather than a width problem: the field was exactly as wide as the grid,
   * so its left and right edges — where the pill's border is, and where the clear
   * button's 32px circle sits — landed on the same vertical line as the covers. At
   * that distance a 1px border reads as part of the artwork beside it, and the clear
   * button looks like it is inside the first cover rather than inside the field.
   *
   * `--shelf-search-inset` is one number used by *both* sides, so the field stays
   * centred on the column: inset one side only would move the whole control, which is
   * the other way to make a row look wrong without anything being at fault.
   *
   * `max-width` subtracts the inset as well, so the field cannot grow back to the
   * full column width on a wide window — a cap that forgot the inset would leave the
   * gutters at the widest size, which is exactly the size where they are least
   * needed.
   */
  margin: 0.35rem auto 0.9rem;
  max-width: calc(
    var(--shelf-measure) - 1.8rem - var(--safe-left) - var(--safe-right) - 2 * var(--shelf-search-inset)
  );
  /*
   * The gutters themselves, and they have to be on the *row* rather than as
   * `padding-inline` on the input: the magnifier and the clear button are absolutely
   * positioned against this box, so padding here would move them out of the field they
   * are drawn inside and leave them floating in the margin.
   */
  padding-inline: var(--shelf-search-inset);
  /*
   * `box-sizing` is what keeps the inset from being *added* to the max-width above:
   * with the default (`content-box`) the field would be `max-width + 2 × inset` wide,
   * i.e. exactly the width it had before — the margin would be paid for by growing the
   * control, and the covers beside it would sit under the clear button again.
   */
  box-sizing: border-box;
}

/*
 * The magnifier inside the search field.
 *
 * ## The bug this rule exists to remove
 *
 * The previous version said `inset-block: 0; margin-block: auto` and the comment above
 * it claimed "the glyph is inline and the box is a line box, so centring the box and
 * centring the glyph are the same instruction". That premise is false, and it is false
 * for a reason that has nothing to do with this glyph: **`position: absolute` forces
 * `display: block`**. The `<span>` was therefore a *block* box, not a line box, and a
 * block box does not centre its line box vertically — it puts it at the top.
 *
 * So the rule did exactly what it said (the box was centred: measured 75.98..120.19 in
 * a field of 75.98..120.19, dead centre) and produced exactly the wrong picture: the
 * line box is 1em tall and sits at the box's top, so a 1.05rem glyph's ink landed with
 * its centre at y=84 while the field's centre was y=98. Fourteen pixels high — the
 * reported "搜索按钮没有垂直对齐".
 *
 * ## Why `grid` and not a transform
 *
 * `place-content: center` centres the *line box* inside the box, which — with the icon
 * font's symmetric ascent/descent (see `tools/icons/build.mjs`) — centres the ink too.
 * That is the same idiom `.icon-button` already uses, so "a glyph in a box" has one
 * answer in this stylesheet rather than two.
 *
 * The alternative, `top: 50%; transform: translateY(-50%)`, also works and is worse: it
 * has to be repeated at every call site and can be omitted at one, it makes the offset a
 * fact about a *transform* rather than about the layout, and it interacts badly with any
 * future padding (the percentage resolves against the padding box while the ink does
 * not). Saying it with the layout system means the field can change height and the
 * magnifier follows without this rule being touched.
 */
.search-glyph {
  position: absolute;
  inset-inline-start: 1.5rem;
  inset-block: 0;
  margin-block: auto;
  /*
   * The box is only as wide as the glyph and as tall as the field. `grid` +
   * `place-content` is what turns "the box is centred" into "the ink is centred" — see
   * `.icon-button` for the same construction.
   */
  display: grid;
  place-content: center;
  width: 1.2rem;
  font-size: 1.05rem;
  color: var(--reader-muted);
  pointer-events: none;
}

.shelf-search input {
  appearance: none;
  flex: 1 1 auto;
  min-width: 0;
  width: 100%;
  border: 1px solid var(--reader-line);
  background: var(--reader-surface);
  color: var(--reader-ink);
  border-radius: 999px;
  /* Room for the glyph on the left and the clear button on the right. */
  padding: 0.62rem 2.4rem 0.62rem 2.15rem;
  /*
   * A field is text, so it gets the text' baseline and the icons positioned inside it
   * are centred against its box instead. The two are only the same line while the
   * field has symmetric padding, which is what the line above guarantees.
   */
  line-height: 1.4;
  font-size: 16px;
  font-family: inherit;
}

/*
 * The platform's own clear affordance, suppressed.
 *
 * A `type=search` input renders a decoration of its own in some browsers and none in
 * others, and the one it renders is *beside* the button this app draws — so the field
 * showed two clear controls, one of them 12px of the browser's own blue at the edge of
 * a control the reader has to hit with a thumb. The app owns this affordance (see
 * `.search-clear`), so the platform's is removed rather than left to duplicate it.
 */
.shelf-search input::-webkit-search-cancel-button,
.shelf-search input::-webkit-search-decoration {
  appearance: none;
  display: none;
}

.shelf-search input::placeholder {
  color: color-mix(in srgb, var(--reader-muted) 85%, transparent);
}

.shelf-search input:focus-visible {
  outline: 2px solid var(--reader-accent);
  outline-offset: 1px;
}

/*
 * The clear button sits *inside* the field rather than beside it.
 *
 * A phone's `type=search` renders its own clear affordance in some browsers and
 * none in others, and the one it renders is 12px of low-contrast glyph at the
 * edge of a control the reader has to hit with a thumb. Owning the button is the
 * only way to get the same thing in both cases.
 */
.search-clear {
  position: absolute;
  inset-inline-end: 0.3rem;
  /*
   * Centred on the field by the geometry both boxes share, not by a transform.
   *
   * `top: 50%` + `translateY(-50%)` is the usual way to do this, and it is a way
   * that has to be repeated at every call site and can be forgotten at one of them.
   * `inset-block: 0` + `margin-block: auto` says the same thing in terms of the
   * containing block, so it stays true if the field's height changes.
   */
  inset-block: 0;
  margin-block: auto;
  width: 1.9rem;
  height: 1.9rem;
  border: 0;
  border-radius: 50%;
  background: color-mix(in srgb, var(--reader-ink) 12%, transparent);
  color: var(--reader-ink);
  font-size: 0.9rem;
  display: grid;
  place-content: center;
  cursor: pointer;
}

/* ---- sections ---- */

.shelf-section {
  padding-inline: calc(0.9rem + var(--safe-left)) calc(0.9rem + var(--safe-right));
  margin-bottom: 1.35rem;
  /*
   * The measure cap, applied to the *content* bands rather than to the scroller.
   *
   * `max-width` + `margin-inline: auto` on the scroller would break `position:
   * sticky` on the toolbar (a scroll container's own box is what sticky is
   * measured against) and would make the scrollbar sit inside the centred column
   * instead of at the window edge. Capping each band keeps both behaviours and
   * still reads as one centred column, because every band shares the same cap.
   */
  max-width: var(--shelf-measure);
  margin-inline: auto;
}

.shelf-section-head {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}

/*
 * A section heading that reads as a heading rather than as bold body text.
 *
 * The reference稿 sets these slightly apart from the content under them with tracking
 * and a muted colour, which is what makes a screen with two lists feel like two
 * sections instead of one long list with a heading in the middle of it. It is a
 * heading *of* the section, so it also loses the underline the toolbar used to carry:
 * two horizontal rules 40px apart made the count row look like a separate band.
 */
.shelf-section-title {
  margin: 0.9rem 0 0.55rem;
  font-size: 0.83rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--reader-muted);
}

/* ---- toolbar: the count and the sort, pinned to their section ---- */

/*
 * Sticky, and deliberately *only* this band. It carries the two controls a reader
 * scrolls back up to change — how many books there are, and in what order — and it
 * is the reason the header above it does not need to stick.
 */
.shelf-toolbar {
  position: sticky;
  inset-block-start: 0;
  z-index: 4;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  /*
   * A hairline under the sticky band, so the covers scrolling beneath it have an
   * edge to pass. Without it the band is invisible until something slides under it,
   * and a translucent band with no boundary reads as a rendering artefact.
   */
  border-bottom: 1px solid color-mix(in srgb, var(--reader-line) 70%, transparent);
  /*
   * The band is full-bleed *within its section*, and the section is capped, so
   * the sticky background matches the column rather than the window. Negative
   * inline margins undo the section's padding so covers scroll under the blur
   * instead of appearing beside it.
   */
  /*
   * Full-bleed with a gutter-sized padding rather than a margin: a sticky band
   * narrower than its scroller lets the covers scroll past *behind* it on either
   * side, which looks like a rendering bug.
   */
  margin-inline: calc(-0.9rem - var(--safe-left)) calc(-0.9rem - var(--safe-right));
  padding: 0.4rem calc(0.9rem + var(--safe-right)) 0.4rem calc(0.9rem + var(--safe-left));
  background: color-mix(in srgb, var(--reader-paper) 88%, transparent);
  backdrop-filter: blur(10px);
}

.shelf-count {
  font-size: 0.75rem;
  white-space: nowrap;
  flex: 0 0 auto;
  font-variant-numeric: tabular-nums;
}

.shelf-sort {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  overflow-x: auto;
  scrollbar-width: none;
  flex: 1 1 auto;
  min-width: 0;
  /* The chips scroll from the right edge, so the row reads as "more this way". */
  justify-content: flex-end;
}

.shelf-sort::-webkit-scrollbar {
  display: none;
}

.shelf-refresh {
  font-size: 0.78rem;
  color: var(--reader-muted);
  text-align: center;
  padding: 0.35rem 0;
}

.shelf-refresh[hidden] {
  display: none;
}

.shelf-status {
  font-size: 0.78rem;
  text-align: center;
  color: var(--reader-muted);
  padding: 0.75rem 0.9rem calc(0.75rem + var(--safe-bottom));
}


/* ---- the pager ----
 *
 * One control, two lists. It lives here rather than beside either list because the
 * shelf and the library must page *identically*: two pagers that are 2px apart, or
 * one with a chevron and one with a triangle, is the drift this stylesheet exists to
 * prevent, and it is the kind of drift nobody notices until they are side by side in
 * a screenshot.
 *
 * ## Why the numbers are pills and the arrows are not
 *
 * The current page is a *state* (where the reader is) and the others are *targets*
 * (where they can go). Drawing all of them the same makes the one fact the control
 * carries — "you are here" — invisible, and the reader has to read every number to
 * find it. So the current page is filled with the accent, and the rest are quiet.
 *
 * ## Why the step arrows are on both sides
 *
 * A long list is read left-to-right and turned the same way: the right chevron is
 * "next", which is the gesture the whole control exists for, and the left one is
 * there so the reader who overshot does not have to find their page number and aim
 * at it.
 */
.shelf-pager,
.manager-pager {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.3rem;
  padding: 0.9rem 0.35rem 0.25rem;
}

/*
 * A page number, sized to the 28px floor rather than to its text.
 *
 * It is a control the reader aims at repeatedly, and 0.72rem of digits in a 16px box
 * is a target that needs the eye rather than the thumb. The box is what is sized, so
 * the numbers stay quiet while the hit area is not.
 */
.pager-page,
.pager-step {
  appearance: none;
  border: 1px solid transparent;
  background: transparent;
  color: var(--reader-ink);
  border-radius: var(--reader-radius);
  min-width: 2rem;
  height: 2rem;
  padding: 0 0.4rem;
  font-size: var(--text-label);
  font-variant-numeric: tabular-nums;
  display: inline-grid;
  place-content: center;
  cursor: pointer;
  touch-action: manipulation;
}

/*
 * The current page: a state, in the same colour the shelf uses for "this is the one".
 *
 * `aria-current="page"` rather than a class, for the same reason the switch uses
 * `aria-pressed`: a class would be a second source of truth for "which page am I on",
 * and the two would eventually disagree — with the disagreement showing up only to a
 * screen reader, which is the worst place for it.
 */
.pager-page[aria-current='page'] {
  background: var(--reader-accent);
  border-color: var(--reader-accent);
  color: #fff;
  font-weight: 600;
}

.pager-page:disabled,
.pager-step:disabled {
  /*
   * `disabled` rather than hidden: the buttons sit in fixed positions, so a control
   * that disappears at page one moves the numbers sideways under the thumb that is
   * on its way to page two.
   */
  opacity: 0.35;
  cursor: default;
}

/*
 * The step arrows carry a glyph, so they take the icon's own line box rules. The
 * `.icon` box is 1em wide with the ink centred in it, and the button centres that
 * box — which is why there is no vertical nudge here and why there must not be one.
 */
.pager-step {
  width: 2rem;
  min-width: 2rem;
  padding: 0;
  font-size: 0.95rem;
}

/* A run of pages the window collapsed. Not a target: there is nothing here to press
   — the two ends of the run are the two pages the reader can reach from here. */
.pager-gap {
  min-width: 1.4rem;
  height: 2rem;
  display: inline-grid;
  place-content: center;
  font-size: var(--text-meta);
  color: var(--reader-muted);
}

@media (prefers-reduced-motion: reduce) {
  /* Nothing animates here, and that is deliberate: a page turn is a new list, and a
     list that fades is a list the reader waits for. This block exists so the next
     person adding a transition to this control has to delete it on purpose. */
  .pager-page,
  .pager-step {
    transition: none;
  }
}

/* ---- the shelf's own section header row ---- */

/* ---- the grid ---- */

/*
 * Fixed minimum with `auto-fill`: the number of columns follows the container, so
 * the same markup works on a phone, a tablet and a desktop without a media query
 * per breakpoint. Density is a *custom property*, not three
 * `grid-template-columns` rules on three classes — one declaration, one value, and
 * the reader's choice cannot disagree with the layout.
 */
.book-grid {
  --shelf-cover-min: 7rem;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(var(--shelf-cover-min), 1fr));
  /*
   * The row gap is larger than the column gap on purpose: a cover and its two
   * lines of text form one block, and equal gaps make the author name look like
   * it belongs to the book below it.
   */
  gap: 1.1rem 0.75rem;
  align-items: start;
}

.book-grid[data-density='compact'] {
  --shelf-cover-min: 5rem;
  gap: 0.9rem 0.6rem;
}

.book-grid[data-density='comfortable'] {
  --shelf-cover-min: 9.5rem;
  gap: 1.35rem 1rem;
}

/*
 * Two columns at the widest, on a desktop.
 *
 * Left alone, `auto-fill` on a 1600px window produces eleven covers a row, each
 * 130px wide and each with a 12-character title — a wall of thumbnails that is
 * harder to scan than a phone's three. Capped, the grid stays a *browsing* surface
 * and the extra width goes to the covers, which is what makes the titles readable
 * again.
 *
 * The number is a `min()` of a count and a width rather than a media query,
 * because the thing that makes eleven columns wrong is not "it is a phone" — it is
 * "the covers got too small", and the two are not the same question.
 */
/*
 * Wider screens get *bigger* covers, not more of them.
 *
 * The failure this avoids is the one every grid has: `auto-fill` turns a wide
 * window into a contact sheet, and a 130px cover with a two-line title is less
 * scannable than a 200px one with the same two lines. The breakpoint moves the
 * size, and the measure cap above bounds the count — the two together are what
 * make a desktop shelf look like a shelf.
 */
@media (min-width: 40rem) {
  .book-grid[data-density='compact'] {
    --shelf-cover-min: 7rem;
  }

  .book-grid:not([data-density='compact']):not([data-density='comfortable']) {
    --shelf-cover-min: 9.5rem;
  }

  .book-grid[data-density='comfortable'] {
    --shelf-cover-min: 12rem;
  }
}

/*
 * The card is a *container*, and the press target is the `.book-open` inside it.
 *
 * It has to be this way once a card carries a second action: a `<button>` inside a
 * `<button>` is invalid markup, and what a browser does with it — hoist the inner one
 * out of its parent — is a layout nobody designed. Both screens that draw a card
 * therefore put the open-target and the extra control as siblings here, which is also
 * why `.is-row` (the library's variant) no longer has to override the whole thing.
 *
 * `position: relative` is what the extra control is placed against.
 */
.book-card {
  position: relative;
  border: 0;
  padding: 0;
  background: transparent;
  color: inherit;
  text-align: start;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  min-width: 0;
  width: 100%;
}

/* The press target: the cover and the two lines under it, and nothing else. */
.book-card .book-open {
  border: 0;
  padding: 0;
  background: transparent;
  color: inherit;
  text-align: start;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  min-width: 0;
  width: 100%;
  font: inherit;
}

/*
 * The card's own actions, as a glyph in the top corner.
 *
 * `opacity` rather than `display`, and always *focusable*: a control that only exists
 * on hover does not exist on the device most of these readers use, and one that is
 * `display: none` until touched cannot be reached by a keyboard or a screen reader at
 * all. Dimmed is legible enough to find and quiet enough not to compete with the
 * cover, which is the thing the reader came for.
 */
.book-card .book-more {
  position: absolute;
  inset-block-start: 0.3rem;
  inset-inline-end: 0.3rem;
  /* 1.75rem = 28px at the root size, which is the smallest hit area the UI review
     accepts and the same floor the top bar's own controls are held to. A corner glyph
     over a cover is exactly the control a finger misses. */
  width: 1.75rem;
  height: 1.75rem;
  border-radius: 999px;
  background: color-mix(in srgb, var(--reader-surface) 82%, transparent);
  color: var(--reader-ink);
  opacity: 0.55;
  backdrop-filter: blur(4px);
  box-shadow: 0 1px 3px rgb(0 0 0 / 0.18);
  transition: opacity var(--motion-duration) var(--motion-ease);
}

.book-card .book-more:hover,
.book-card .book-more:focus-visible,
.book-card .book-more:active {
  opacity: 1;
}

/* A pointer can hover, so the glyph can afford to be invisible until it does; a
   finger cannot, so the rule is scoped to hosts that have one. */
@media (hover: hover) {
  .book-card .book-more {
    opacity: 0;
  }
}

/*
 * The cover.
 *
 * `aspect-ratio` rather than a fixed height, so the cover scales with the column.
 * No border: a 1px hairline on a cover that already has a shadow reads as a frame
 * around a photo, and the whole point of the shadow is that the cover looks like
 * an object lying on the paper.
 */
/*
 * The cover.
 *
 * `display: grid` with `place-items: stretch` and *not* `center`, which is a
 * distinction worth stating because getting it wrong is invisible in the
 * stylesheet and obvious on screen: a centred grid item makes the implicit column
 * shrink to its content, so a cover containing only a title collapsed to 45px
 * inside a 122px card while a cover containing an image filled it. The card was
 * the right size and the cover was not, so every row looked ragged for no
 * reason. Stretching the item and centring the *text* inside the placeholder is
 * what makes both cases fill the card.
 */
.book-card .cover {
  position: relative;
  /* Explicit, because inside a flex column an `aspect-ratio` box with no width
     shrink-wraps to its content: a cover holding only a title collapsed to 42px
     in a 122px card, while one holding an image filled it, so every row of an
     all-TXT shelf came out ragged. */
  width: 100%;
  aspect-ratio: 2 / 3;
  border-radius: 8px;
  overflow: hidden;
  background: color-mix(in srgb, var(--reader-line) 70%, var(--reader-surface));
  box-shadow: 0 1px 2px rgb(0 0 0 / 0.14), 0 3px 10px rgb(0 0 0 / 0.06);
  display: grid;
  place-items: stretch;
  transition:
    transform var(--motion-duration) var(--motion-ease),
    box-shadow var(--motion-duration) var(--motion-ease);
}

.book-card .book-open:active .cover {
  transform: scale(0.975);
  box-shadow: 0 1px 2px rgb(0 0 0 / 0.16);
}

.book-card .cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

/*
 * A book with no cover art — every TXT file, plenty of PDFs.
 *
 * The title is drawn *as* the cover rather than as a broken-image icon, because
 * "this book has no cover" and "this library is broken" look identical otherwise,
 * and the first one is a fact about the book. A tinted panel with the title set in
 * it also makes the shelf scannable at a glance, which a grey box does not.
 */
.book-card .cover .placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.7rem 0.55rem;
  font-size: 0.78rem;
  font-weight: 500;
  line-height: 1.35;
  text-align: center;
  color: color-mix(in srgb, var(--reader-ink) 72%, transparent);
  background:
    linear-gradient(
      150deg,
      color-mix(in srgb, var(--reader-accent) 16%, var(--reader-surface)) 0%,
      color-mix(in srgb, var(--reader-accent) 6%, var(--reader-line)) 100%
    );
  /* Clipped rather than scrolled: a title set to fourteen lines stops being a
     cover and starts being a paragraph in the wrong place. */
  overflow: hidden;
  word-break: break-word;
}

.book-card .format-badge {
  position: absolute;
  inset-block-end: 0.3rem;
  inset-inline-end: 0.3rem;
  background: rgb(0 0 0 / 0.58);
  color: #fff;
  border-radius: 4px;
  padding: 0.05rem 0.3rem;
  font-size: 0.6rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  backdrop-filter: blur(4px);
}

.book-card .title {
  font-size: 0.8rem;
  line-height: 1.3;
  font-weight: 520;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  /* Two lines are always occupied, so the author names of a row of covers line
     up even when one title is short — a ragged baseline under a grid is the
     difference between "a shelf" and "a list". */
  min-height: 2.6em;
}

.book-card .author {
  font-size: 0.7rem;
  color: var(--reader-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.book-grid[data-show-author='false'] .book-card .author {
  display: none;
}

.book-grid[data-show-progress='false'] .cover-progress {
  display: none;
}

/*
 * Progress on the cover.
 *
 * Absolute rather than a row under the title: the point of the bar is to be
 * readable while skimming a shelf, and a 3px line under 11px of author text is not
 * glancing distance from a cover. It sits at the bottom edge of the cover art,
 * where the eye already is.
 */
.book-card .cover-progress {
  position: absolute;
  inset-inline: 0;
  inset-block-end: 0;
  height: 4px;
  background: rgb(0 0 0 / 0.35);
}

.book-card .cover-progress span {
  display: block;
  height: 100%;
  background: var(--reader-accent);
}

/* ---- continue reading: removed, on purpose ----
 *
 * There used to be a horizontal 继续阅读 row above the grid here: ten cards, the same
 * ten books that are already on the shelf below, drawn a second time in a strip.
 * It is gone, and the space it took is the point — the shelf is a grid of covers and
 * the question the strip answered ("where was I") is now answered by the *order* of
 * that grid, because 最近阅读 is the default sort. A row that duplicates ten of the
 * sixty covers under it is not a shortcut, it is the first thing the reader has to
 * scroll past to reach the books.
 *
 * The progress bar it drew is still drawn: on the cover of every card that has been
 * started, from the same local mirror, which is where it was always more useful.
 * The timestamps the strip was built from are still fetched, and are now the sort
 * key (see `shelf-screen.tsx`), so nothing came off the wire.
 */

/* ---- the first paint ---- */

/*
 * The shelf's shape, before the shelf exists.
 *
 * Drawn in the reader's own density so the fill-in is a fill-in: a skeleton in the
 * wrong grid makes the reader watch the layout move twice and stops trusting the
 * first one. The shimmer is animation only — under `prefers-reduced-motion` it
 * becomes a flat tint, which still says "loading" without moving.
 */
.book-grid.is-skeleton {
  pointer-events: none;
}

.book-grid.is-skeleton .cover {
  box-shadow: none;
}

.skeleton-line {
  height: 0.62rem;
  border-radius: 3px;
  background: color-mix(in srgb, var(--reader-line) 80%, var(--reader-surface));
  min-height: 0;
}

.skeleton-line.short {
  width: 55%;
}

.book-grid.is-skeleton .cover,
.skeleton-line {
  background-image: linear-gradient(
    100deg,
    transparent 20%,
    color-mix(in srgb, var(--reader-ink) 5%, transparent) 50%,
    transparent 80%
  );
  background-size: 220% 100%;
  animation: shelf-shimmer 1.5s linear infinite;
}

@keyframes shelf-shimmer {
  from {
    background-position: 140% 0;
  }
  to {
    background-position: -40% 0;
  }
}

/* ---- empty state ---- */

/*
 * `margin: auto` inside the section, so the box is centred in whatever height is
 * left rather than pinned under the toolbar — which is where the old version put
 * it, half a screen above the fold on a phone.
 */
.empty-state {
  margin: 2.5rem auto auto;
  max-width: 20rem;
  text-align: center;
  color: var(--reader-ink);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.35rem;
}

.empty-state p {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 550;
}

.empty-state p.muted {
  font-size: 0.78rem;
  font-weight: 400;
  line-height: 1.5;
}

.empty-glyph {
  font-size: 2.4rem;
  /*
   * A block of its own, so the flex column's `gap` owns the space between the glyph and
   * the text rather than the glyph's own line box.
   */
  display: block;
  opacity: 0.35;
}

.empty-actions {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 0.85rem;
}

/* ---- shelf settings sheet ---- */

.shelf-settings .switch-field {
  flex-direction: row;
  align-items: center;
  gap: 0.75rem;
}

.shelf-settings .switch-text {
  flex: 1 1 auto;
  min-width: 0;
  font-size: 0.9rem;
}

.shelf-settings .switch-text .muted {
  font-size: 0.72rem;
  margin-top: 0.15rem;
}

/*
 * The switch.
 *
 * A 2.6rem pill with the knob drawn by `::after`. `aria-pressed` drives both the
 * colour and the knob position, so there is exactly one source of truth for "is
 * this on" — a separate class would be a second one, and the two would eventually
 * disagree.
 */
.shelf-settings .switch {
  flex: 0 0 auto;
  position: relative;
  width: 2.7rem;
  height: 1.6rem;
  border-radius: 1rem;
  border: 0;
  background: var(--reader-line);
  cursor: pointer;
  transition: background var(--motion-duration) var(--motion-ease);
}

.shelf-settings .switch::after {
  content: '';
  position: absolute;
  top: 0.2rem;
  inset-inline-start: 0.2rem;
  width: 1.2rem;
  height: 1.2rem;
  border-radius: 50%;
  background: var(--reader-surface);
  box-shadow: 0 1px 2px rgb(0 0 0 / 0.25);
  transition: inset-inline-start var(--motion-duration) var(--motion-ease);
}

.shelf-settings .switch[aria-pressed='true'] {
  background: var(--reader-accent);
}

.shelf-settings .switch[aria-pressed='true']::after {
  inset-inline-start: 1.3rem;
}

@media (prefers-reduced-motion: reduce) {
  /* The chrome's own show/hide is a state change, not decoration: it still has to
     happen, it just does not have to be animated. Collapsing every duration to a
     hair keeps the reader's preference without leaving the bands half-way. */
  .topbar,
  .footer,
  .reader-rail {
    transition-duration: 1ms;
    animation: none;
  }

  .shelf-settings .switch,
  .shelf-settings .switch::after {
    transition: none;
  }

  .book-card .cover,
  .book-card .book-more,
  .book-grid.is-skeleton .cover,
  .book-grid.is-skeleton .skeleton-line {
    animation: none;
    transition: none;
  }
}

/* ---- panels: a bottom sheet, half the screen ----
 *
 * These used to be `inset: 0` — full-screen opaque pages that replaced the book.
 * That is a defensible pattern for a *destination* and the wrong one for a
 * *control*: choosing a chapter or nudging the font size is an adjustment to the
 * page underneath, and a full-screen panel makes the reader leave the page to make
 * it — then come back to a re-laid-out chapter with no memory of what it looked
 * like before. The panel is therefore a sheet over the *lower half* of the reading
 * area, and the top half stays readable, which is what makes the change visible
 * while it is being made.
 *
 * Three things follow from that and are not decoration:
 *
 *  - **A scrim**, because a sheet without one reads as part of the page. It is
 *    also the tap target that closes the sheet, which is the second way out, along
 *    with the ✕ in the header.
 *  - **A handle**, because a sheet that rises from the bottom is understood to be
 *    draggable, and a drag target with nothing to grab is a sheet the reader
 *    cannot close the way they expect. (The drag itself is not implemented; the
 *    handle is the *affordance*, and the scrim and the ✕ are the two real ways out.
 *    Promising a drag that does not exist would be worse than not drawing it, so
 *    the handle is a visual cue and the sheet's own scroll is what moves.)
 *  - **A height that leaves the top of the page alone.** `min(70%, ...)` rather
 *    than a fixed viewport fraction: the contents list of a 1200-chapter book wants
 *    all the room it can get, and the settings list of eleven rows does not want
 *    more than it needs.
 */

.scrim {
  position: absolute;
  inset: 0;
  z-index: var(--reader-layer-panel);
  background: color-mix(in srgb, #000 42%, transparent);
  animation: scrim-in var(--motion-duration) var(--motion-ease);
}

@keyframes scrim-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

.panel {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  z-index: var(--reader-layer-panel);
  display: flex;
  flex-direction: column;
  min-height: 0;
  /* Half the reading area, and never more than three quarters of it: the reader
     has to be able to see the page they are adjusting, and a sheet that covers
     everything is the full-screen panel this replaced. */
  height: min(62%, 34rem);
  max-height: 78%;
  background: var(--reader-surface);
  border-top: 1px solid var(--reader-line);
  border-radius: 16px 16px 0 0;
  box-shadow: 0 -14px 36px color-mix(in srgb, #000 26%, transparent);
  animation: sheet-in var(--motion-duration) var(--motion-ease);
}

@keyframes sheet-in {
  from { transform: translateY(100%); }
  to { transform: translateY(0); }
}

.panel[hidden] {
  display: none;
}

/* The grab handle. Decorative, so it is `aria-hidden` in the markup. */
.panel-grip {
  flex: 0 0 auto;
  width: 2.25rem;
  height: 0.25rem;
  margin: 0.5rem auto 0.125rem;
  border-radius: 999px;
  background: var(--reader-line);
}

.panel-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.25rem 0.5rem 0.5rem 0.9rem;
  border-bottom: 1px solid var(--reader-line);
}

.panel-header h2 {
  margin: 0;
  font-size: var(--text-title);
  font-weight: 600;
}

/* The count beside the title. Right-aligned against the ✕ rather than next to the
   title, so the header reads as "title … count … close" and the closing control
   stays exactly where the reader's thumb expects it. */
.panel-subtitle {
  flex: 1 1 auto;
  text-align: end;
  font-size: var(--text-meta);
  color: var(--reader-muted);
  font-variant-numeric: tabular-nums;
}

.panel-body {
  flex: 1 1 auto;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  /* `overscroll-behavior: contain` stops a flick at the end of the list from
     scrolling the *chapter* behind the sheet, which is the classic bottom-sheet
     annoyance: the list stops moving, the text underneath starts, and the reader
     has lost their place. */
  overscroll-behavior: contain;
  padding: var(--space-3) 0.9rem calc(var(--space-3) + var(--safe-bottom));
}

.toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

/* A row is a row, not a full-width button with a divider under it.
 *
 * The list is long and the rows are short, so the divider was doing the work a
 * rhythm should: rows are separated by their own spacing, and the *current* row is
 * marked once, loudly, instead of every row being marked equally. */
.toc-list li button {
  width: 100%;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-align: start;
  border: 0;
  background: transparent;
  color: var(--reader-ink);
  padding: 0.55rem 0.6rem;
  border-radius: var(--reader-radius);
  font-size: var(--text-body);
  line-height: 1.35;
  cursor: pointer;
  touch-action: manipulation;
}

.toc-list li button:hover {
  background: color-mix(in srgb, var(--reader-ink) 6%, transparent);
}

.toc-list li button[aria-current='true'] {
  color: var(--reader-accent);
  font-weight: 600;
  background: color-mix(in srgb, var(--reader-accent) 12%, transparent);
}

/* A row for a chapter the loaded window cannot reach. It is still listed — the
   book does have that chapter — but it must not look tappable, because tapping it
   is the case the panel used to accept in silence. */
.toc-list li button[data-unreachable='true'] {
  opacity: 0.55;
  cursor: default;
}

.toc-list li button[data-unreachable='true']:hover {
  background: transparent;
}

/* A chapter's title, and the whole-book position beside it. The position is what
   makes a long list navigable: it is the only number that tells the reader how far
   in they are while they scroll. */
.toc-list li .toc-index {
  flex: 0 0 auto;
  min-width: 2.4rem;
  font-size: var(--text-meta);
  color: var(--reader-muted);
  font-variant-numeric: tabular-nums;
}

.toc-list li .toc-label {
  flex: 1 1 auto;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ---- footer / progress ----
 *
 * The footer has two rows and they are doing different jobs, so they are laid out
 * differently rather than as two rows of the same thing:
 *
 *  - the *control* row (☰ ‹ chapter › ⚙) is what the reader aims at, so it is
 *    centred and its controls are one size down from the topbar's — four 2.5rem
 *    controls plus a label is more than a 360px phone has;
 *  - the *readout* row (章节 / 页数 / 百分比) is what the reader glances at, so it
 *    is a single line of small tabular numbers spread across the width, with the
 *    three numbers in the three positions they will always be in. A readout that
 *    moves around as its values change is a readout the reader has to search.
 */

/*
 * Hidden: the footer slides down and fades, exactly as the header does, and on the
 * same attribute — see `.reader-screen[data-chrome='hidden']`. The progress bar goes
 * with it rather than staying as a hairline: it is part of the chrome, and a
 * two-pixel band left behind at the bottom of the screen is the one thing that makes
 * "沉浸式" look broken.
 *
 * Like the header it gives no height back, because it took none: the reading column
 * keeps the same block inset in both states, so the last line of a page is in the
 * same place whether the toolbar is up or down. It is drawn as a layer over the
 * page, with its own surface colour, so the lines it covers are *behind* it rather
 * than pushed above it.
 */
.reader-screen[data-chrome='hidden'] .footer {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  border-top-color: transparent;
  transform: translateY(100%);
}

.footer {
  /* Over the page at the bottom edge, the same arrangement as the top bar. */
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  z-index: var(--reader-layer-bar);
  /* The same floating surface as the top bar — over the page, see above. */
  background: var(--reader-surface-float);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  /* A hairline that survives a dark theme and a bright page equally: one solid
     colour has to fight whichever side it borders, and this is the one place the
     footer meets the paper. */
  border-top: 1px solid color-mix(in srgb, var(--reader-line) 80%, transparent);
  padding-bottom: var(--safe-bottom);
  /* The same two properties as the header, and for the same reason: nothing here
     changes the page's geometry. */
  transition:
    opacity var(--motion-duration) var(--motion-ease),
    transform var(--motion-duration) var(--motion-ease),
    visibility 0s linear var(--motion-duration);
}

/*
 * The scrubber row: a draggable progress slider and the page readout beside it.
 *
 * The slider replaces the old 3px bar. That bar could only *report* the position;
 * a reader who wanted the end of a long chapter had to tap "next" forty times. A
 * range input is the one control that answers "take me there" in a single gesture,
 * and it is native — the thumb, the track, the drag physics and the accessibility
 * (arrow keys, `aria-valuenow`) all come with it rather than being reimplemented.
 */
.progress-row {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--reader-band-inset) 0.25rem;
}

.progress-scrubber {
  flex: 1 1 auto;
  min-width: 0;
  /* A range input carries a user-agent inline margin, which put the track 2px
     inside the row's own padding while the page readout opposite it sat flush with
     it — a visible hairline of misalignment on the row the reader asked to have
     aligned. The row's padding is the inset; the control adds none of its own. */
  margin-inline: 0;
  /* Native range inputs default to a chunky, theme-blind widget; `appearance: none`
     is what lets the tokens below draw it. The track is drawn on the element and
     the thumb on `::-webkit-slider-thumb` / `::-moz-range-thumb`, which are two
     separate rule sets because the two engines never agreed on a shared one. */
  appearance: none;
  -webkit-appearance: none;
  height: 1.5rem;
  background: transparent;
  cursor: pointer;
  touch-action: manipulation;
}

.progress-scrubber::-webkit-slider-runnable-track {
  height: 0.3rem;
  border-radius: 0.15rem;
  background: color-mix(in srgb, var(--reader-line) 70%, transparent);
}

.progress-scrubber::-moz-range-track {
  height: 0.3rem;
  border-radius: 0.15rem;
  background: color-mix(in srgb, var(--reader-line) 70%, transparent);
}

.progress-scrubber::-webkit-slider-thumb {
  appearance: none;
  -webkit-appearance: none;
  width: 1.1rem;
  height: 1.1rem;
  /* Pull the thumb up onto the middle of the track: the track is 0.3rem and the
     thumb 1.1rem, so half the difference is the offset. Without this the thumb
     sits below the line it is supposed to ride. */
  margin-top: -0.4rem;
  border-radius: 50%;
  background: var(--reader-surface);
  border: 2px solid var(--reader-accent);
  box-shadow: 0 1px 4px color-mix(in srgb, #000 18%, transparent);
}

.progress-scrubber::-moz-range-thumb {
  width: 1.1rem;
  height: 1.1rem;
  border-radius: 50%;
  background: var(--reader-surface);
  border: 2px solid var(--reader-accent);
  box-shadow: 0 1px 4px color-mix(in srgb, #000 18%, transparent);
}

.progress-scrubber:focus-visible {
  outline: var(--focus-ring);
  outline-offset: var(--focus-offset);
}

/* The page readout: tabular so "第 9/32 页" does not twitch sideways as the
   denominator changes width. */
.progress-page {
  flex: 0 0 auto;
  font-size: var(--text-meta);
  font-variant-numeric: tabular-nums;
  color: var(--reader-muted);
  white-space: nowrap;
}

/*
 * The chapter navigation row.
 *
 * Three cells: previous chapter, the reading progress as a label, next chapter.
 * The two buttons are text-with-chevron rather than bare chevrons — the whole row
 * is a labelled destination, and a bare "‹" beside a bare "›" is a guess.
 */
.footer-row.chapter-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding: 0.15rem var(--reader-band-inset) 0.65rem;
}

/*
 * The chapter buttons' horizontal padding is *zero*.
 *
 * They used to carry `0.4rem` of their own on top of the row's padding, so the
 * label "上一章" started 0.4rem further in than the page readout above it and the
 * row's two ends disagreed with the scrubber row's. The padding was there to give
 * the button a bigger hit area — which it still gets, vertically: the row's height
 * is 0.45rem of padding plus a line, and the *width* is now the label's own. A
 * button whose target is as wide as its text is the right target for a row that is
 * read as one line of controls.
 */
.nav-chapter {
  display: inline-flex;
  align-items: center;
  gap: 0.15rem;
  border: 0;
  background: transparent;
  color: var(--reader-ink);
  font: inherit;
  font-size: var(--text-label);
  padding: 0.45rem 0;
  border-radius: var(--reader-radius);
  cursor: pointer;
  touch-action: manipulation;
  white-space: nowrap;
}

.nav-chapter:active {
  background: color-mix(in srgb, var(--reader-ink) 8%, transparent);
}

.nav-chapter:disabled {
  opacity: 0.35;
  cursor: default;
}

.nav-progress {
  flex: 1 1 auto;
  text-align: center;
  font-size: var(--text-label);
  color: var(--reader-muted);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ---- quick-action rail ----
 *
 * The column of controls that shows and hides **with** the two bars, not instead of
 * them. It used to be drawn only while the chrome was hidden, which made it the one
 * piece of chrome that survived immersion: a reader who tapped to get "just the
 * page" still had a floating column over the right edge of the text. The rail holds
 * the two adjustments a reader makes from the page itself (主题 / 字号) plus 听书, so it
 * belongs to the same state the bars do — the reader has asked for the controls — and
 * it goes with them. The five destinations that used to be here (目录 / 字体 / 行距 /
 * 页边距 / 设置) are gone: all five open or reach a sheet, and a second, worse copy of
 * the settings panel floating over the text is not a shortcut.
 *
 * Positioned in the *page margin* rather than over the text, which is why it can be
 * on screen while a reader is reading: the reading column is capped by
 * `--reader-measure`, so on anything wider than a phone there is a genuine gutter to
 * put it in. On a phone there is not, and the rail floats over the right edge of the
 * text — deliberately, because the alternative is not having the controls at all,
 * and the buttons are translucent discs that a reader reads *through* rather than
 * around.
 *
 * Its vertical position is a compromise made visible: roughly a third of the way
 * down, which is where the thumb of a hand holding a phone at the bottom lands and
 * where a hand holding a tablet at the side reaches. It is not centred, because the
 * centre of the screen is where the reading is.
 *
 * The collapse is the *same* mechanism as the bars': a height/opacity/visibility
 * transition gated on `data-chrome`, so the three bands cannot disagree about
 * whether the chrome is on screen. `animation` for entry was replaced by a
 * transition for the same reason: an animation cannot be reversed mid-flight, so a
 * reader who tapped twice quickly left the rail visible over a hidden toolbar.
 */

.reader-rail {
  position: absolute;
  inset-inline-end: calc(0.35rem + var(--safe-right));
  /*
   * Below the top of the screen, within comfortable
   * reach: a hand holding a phone at the bottom of the screen reaches this band.
   * Keeping controls at the side also leaves the centre clear for reading.
   */
  top: calc(22% + var(--safe-top));
  /*
   * A ceiling, and it is the whole of why the rail can be trusted to show what it
   * contains.
   *
   * Without one the column was as tall as its buttons and simply ran off the bottom
   * of a short screen: a phone in landscape, or a phone whose status bar and
   * browser chrome leave 500px, showed the first four controls and nothing else —
   * with no scrollbar, no fade and no hint that there was more. That is the
   * standing report ("竖排工具栏显示为 主题切换、听书") described exactly: a reader who
   * counts what they can see and concludes that is what the rail does.
   *
   * `--reader-chrome-bottom` and `--reader-chrome-top` are the same two numbers the
   * reading column reserves for the bars, so the rail cannot extend under either of
   * them however many controls it holds; `max-height` rather than `height` so a rail
   * with three buttons is three buttons tall and does not float in an empty column.
   */
  max-height: calc(100% - 22% - var(--safe-top) - var(--reader-chrome-bottom) - 0.5rem);
  overflow-y: auto;
  /*
   * `overscroll-behavior: contain`, so reaching the end of the rail does not hand
   * the rest of the gesture to the page underneath it. Without it, a flick that
   * finds the last button turns into a chapter scroll — the reader's finger was on a
   * control and the book moved.
   */
  overscroll-behavior: contain;
  z-index: var(--reader-layer-rail);
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding: 0.2rem;
  opacity: 1;
  transform: none;
  transition:
    opacity var(--motion-duration) var(--motion-ease),
    transform var(--motion-duration) var(--motion-ease),
    visibility 0s linear;
}

/*
 * The rail's scrollbar is *drawn*, not hidden.
 *
 * `scrollbar-width: none` is the usual treatment for a decorative strip, and it is
 * precisely wrong here: a control that can only be found by scrolling has to look
 * scrollable, or the reader never learns it is there — which is the bug above. A
 * hairline on a translucent column is also the honest amount of chrome for it: the
 * rail floats over the text, and a 12px opaque gutter would be a band of the page
 * the reader cannot see through for no information.
 */
.reader-rail::-webkit-scrollbar {
  inline-size: 3px;
}

.reader-rail::-webkit-scrollbar-thumb {
  background: color-mix(in srgb, var(--reader-ink) 22%, transparent);
  border-radius: 999px;
}

/*
 * Hidden: it slides out to the right and fades, the direction its own entry motion
 * came from, so a reader who taps twice sees one movement rather than two.
 *
 * Gated on the screen's own `data-chrome`, exactly like `.topbar` and `.footer`.
 * One attribute, three bands: they cannot disagree about whether the chrome is on
 * screen, which is the failure mode ("only the toolbar collapsed") that a second
 * source of truth produces. `visibility: hidden` lands at the *end* of the fade so
 * a control that is on its way off the screen cannot be tapped or reached by a
 * screen reader, and `pointer-events: none` covers the interval.
 */
.reader-screen[data-chrome='hidden'] .reader-rail {
  visibility: hidden;
  opacity: 0;
  transform: translateX(0.5rem);
  pointer-events: none;
  transition:
    opacity var(--motion-duration) var(--motion-ease),
    transform var(--motion-duration) var(--motion-ease),
    visibility 0s linear var(--motion-duration);
}

.rail-button {
  display: grid;
  place-items: center;
  width: 2.75rem;
  height: 2.75rem;
  padding: 0;
  border: 1px solid color-mix(in srgb, var(--reader-line) 70%, transparent);
  border-radius: 50%;
  /*
   * Translucent, because the rail sits over text on a phone. A solid disc is a hole
   * in the page; a blurred one is a control the reader can see the paragraph
   * through, which is what makes it possible to leave it there.
   */
  background: color-mix(in srgb, var(--reader-surface) 78%, transparent);
  backdrop-filter: blur(6px);
  color: var(--reader-ink);
  font-size: 1.05rem;
  cursor: pointer;
  touch-action: manipulation;
  box-shadow: 0 2px 8px color-mix(in srgb, #000 12%, transparent);
  transition: transform var(--motion-duration) var(--motion-ease), background var(--motion-duration) var(--motion-ease);
}

.rail-button:active {
  transform: scale(0.92);
  background: color-mix(in srgb, var(--reader-surface) 96%, transparent);
}

/* On a wide screen the rail moves into the gutter the measure leaves, so it is
   beside the text rather than on top of it. `--reader-measure` is the same token
   the column uses, so the two cannot disagree about where the text ends. */
@media (min-width: 60rem) {
  .reader-rail {
    inset-inline-end: max(0.75rem, calc((100% - var(--reader-measure)) / 2 - 3.5rem));
  }
}

/* ---- quick rows in the settings sheet ---- */

.quick-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-2);
  padding: 0 0 var(--space-2);
}

.quick-button {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.15rem;
  padding: 0.55rem 0.3rem;
  border: 1px solid color-mix(in srgb, var(--reader-line) 80%, transparent);
  border-radius: var(--reader-radius);
  background: color-mix(in srgb, var(--reader-ink) 4%, transparent);
  color: var(--reader-ink);
  font: inherit;
  cursor: pointer;
  touch-action: manipulation;
}

.quick-button:active {
  background: color-mix(in srgb, var(--reader-ink) 10%, transparent);
}

.quick-button:disabled {
  opacity: 0.55;
  cursor: default;
}

.quick-button .quick-label {
  font-size: var(--text-meta);
  color: var(--reader-muted);
}

.quick-button .quick-value {
  font-size: var(--text-label);
  font-variant-numeric: tabular-nums;
}

/* ---- read-aloud bar ---- */

/*
 * The bar floats over the bottom of the page, and that is a *fix*, not a style
 * choice.
 *
 * It used to be an ordinary flex child of `.reader-screen`. The screen is a flex
 * column whose first child is `.stage-host`, and the stage host is
 * `position: absolute; inset: 0` — it covers the whole screen so the page does not
 * resize when the bars come and go. A static sibling in that column is therefore
 * laid out *behind* the reading surface, which paints at `--reader-layer-page`.
 * The bar was drawn, its buttons were focusable, and the stage was painted over
 * all of it: the reader could see the sentence being read and could not press
 * anything. That is the whole of "没法停止" — the stop button existed and was
 * unreachable, which reads as a control that does nothing.
 *
 * So it is a layer with the bars' own z-index (`--reader-layer-bar`), pinned above
 * the bottom edge and above the footer's own height, which is where its controls
 * have to be to be hit by a thumb. Unlike the footer it is *not* hidden with the
 * chrome: a reader listening while walking needs play/pause without the header
 * covering the sentence being read.
 *
 * `--reader-chrome-bottom` is the footer's own height, read here rather than
 * guessed, so the two bands cannot overlap however the footer's rows change.
 */
.tts-bar {
  position: absolute;
  inset-inline: 0;
  bottom: var(--reader-chrome-bottom);
  z-index: var(--reader-layer-bar);
  display: flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.5rem;
  background: var(--reader-surface-float);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-top: 1px solid var(--reader-line);
}

.tts-bar[hidden] {
  display: none;
}

/*
 * Two rows, stacked: the transport controls, then the sentence with its scrubber.
 *
 * A column rather than a single flex row because the single row could not fit —
 * see the comment on `.tts-bar`. The two rows take the full width of the bar, so
 * the five controls split it evenly and none of them is ever clipped.
 */
.tts-bar .tts-row {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  min-width: 0;
}

.tts-bar .tts-controls {
  /* Every control the same width, including the chip: a row whose cells are
     sized by their contents leaves the widest one (the ✕, whose label is a
     glyph) flush to the edge and the others bunched. Equal cells read as one
     transport, which is what the row is. */
  gap: var(--space-1);
}

.tts-bar .tts-controls > * {
  flex: 1 1 0;
  min-width: 0;
}

/* The chip is a text control in a row of icons, so its own padding is dropped:
   the cell's width is the equal share, not the label's. */
.tts-bar .tts-chip {
  appearance: none;
  border: 1px solid color-mix(in srgb, var(--reader-line) 90%, transparent);
  background: var(--reader-surface);
  color: var(--reader-muted);
  border-radius: 999px;
  height: 2.75rem;
  min-width: 0;
  padding: 0 0.4rem;
  font: inherit;
  font-size: var(--text-meta);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  cursor: pointer;
  touch-action: manipulation;
}

.tts-bar .tts-chip:active {
  background: color-mix(in srgb, var(--reader-ink) 8%, transparent);
}

/*
 * Stop is the one destructive control on the bar and it is drawn as such.
 *
 * It is not a warning colour: this is a reading app, and a red button in the
 * middle of a page is a louder statement than "stop the voice". The accent fill
 * is enough to separate it from the three transport buttons beside it, which is
 * the whole job — the reader who wants the voice to stop has to be able to pick
 * this control out of a row of five at a glance.
 */
.tts-bar .tts-stop {
  background: color-mix(in srgb, var(--reader-accent) 16%, transparent);
  border-color: color-mix(in srgb, var(--reader-accent) 45%, transparent);
  color: var(--reader-ink);
}

.tts-bar .tts-progress {
  gap: var(--space-2);
  padding-inline: 0.15rem;
}

.tts-bar .tts-text {
  flex: 0 1 auto;
  max-width: 40%;
  font-size: 0.78rem;
  color: var(--reader-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.tts-range {
  flex: 1 1 auto;
  min-width: 0;
  margin: 0;
  accent-color: var(--reader-accent);
}

/*
 * A chip: a small, pressable *choice*.
 *
 * The pressed state did not exist. `aria-pressed` was set correctly and read by
 * screen readers, and nothing drew it — so the shelf's four sort chips looked
 * identical whichever one was in force, and the only way to find out how the list
 * was ordered was to read the subtitle above it. `aria-pressed` drives the fill for
 * the same reason the switch uses it: one source of truth for "is this on".
 */
.chip {
  appearance: none;
  border: 1px solid color-mix(in srgb, var(--reader-line) 90%, transparent);
  background: var(--reader-surface);
  color: var(--reader-muted);
  border-radius: 999px;
  padding: 0.3rem 0.7rem;
  font-size: 0.72rem;
  white-space: nowrap;
  cursor: pointer;
}

.chip[aria-pressed='true'] {
  background: color-mix(in srgb, var(--reader-accent) 12%, var(--reader-surface));
  border-color: color-mix(in srgb, var(--reader-accent) 45%, transparent);
  color: var(--reader-accent);
  font-weight: 600;
}

@media (hover: hover) and (pointer: fine) {
  .chip[aria-pressed='true']:hover {
    /* The pressed chip keeps its own fill: hover must not erase the state, which is
       the one fact the control carries. */
    background: color-mix(in srgb, var(--reader-accent) 18%, var(--reader-surface));
  }
}

/* ---- settings panel structure ---- */

/*
 * A section heading inside a sheet.
 *
 * Sticky, and that is the one thing it does. The settings sheet is longer than the
 * half-screen it lives in, so a reader scrolling to find 亮度 passes 排版 and 翻页
 * on the way — and without a sticky heading they arrive at a row with no idea which
 * group it belongs to. It is also the only sticky thing in the sheet, so it does
 * not compete with the panel header.
 */
.section-title {
  position: sticky;
  top: 0;
  z-index: 1;
  margin: 0 -0.9rem var(--space-2);
  padding: var(--space-2) 0.9rem 0.35rem;
  background: var(--reader-surface);
  border-bottom: 1px solid color-mix(in srgb, var(--reader-line) 60%, transparent);
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--reader-muted);
}

.section-title:first-child {
  margin-top: -0.35rem;
}

/* A row: label on the left, control on the right, on one line where it fits.
 *
 * The old rows were a column — a label, then the control under it — which is right
 * for a text field and wasteful for a segmented control or a slider: eleven rows of
 * two lines each is a sheet that scrolls twice as far as it needs to, and the reader
 * has to re-read every label to find the one control they came for. */
.field {
  display: grid;
  grid-template-columns: minmax(4.5rem, max-content) 1fr;
  align-items: center;
  gap: var(--space-2) var(--space-3);
  margin-bottom: var(--space-2);
}

.field:last-child {
  margin-bottom: 0;
}

.field label {
  font-size: var(--text-label);
  color: var(--reader-muted);
  white-space: nowrap;
}

/* A control that needs the full width takes it, by asking for it. */
.field.is-stacked {
  grid-template-columns: 1fr;
}

.field > .segmented,
.field > select,
.field > input[type='range'] {
  justify-self: stretch;
  min-width: 0;
}

.field[hidden] {
  display: none;
}

/* ---- status ---- */

/* ---- misc ---- */

.empty-state,
.centered-form {
  margin: auto;
  max-width: 24rem;
  width: 100%;
  padding: 1.5rem;
  text-align: center;
}

.centered-form {
  text-align: start;
}

.notice {
  background: color-mix(in srgb, var(--reader-accent) 12%, var(--reader-surface));
  border-radius: var(--reader-radius);
  padding: 0.6rem 0.75rem;
  font-size: 0.82rem;
  margin-bottom: 0.9rem;
}

.muted {
  color: var(--reader-muted);
}

.spinner {
  width: 1.5rem;
  height: 1.5rem;
  border: 2px solid var(--reader-line);
  border-top-color: var(--reader-accent);
  border-radius: 50%;
  animation: spin 700ms linear infinite;
  margin: 1rem auto;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.segmented {
  display: flex;
  border: 1px solid var(--reader-line);
  border-radius: var(--reader-radius);
  overflow: hidden;
}

.segmented button {
  flex: 1 1 0;
  border: 0;
  background: var(--reader-surface);
  color: var(--reader-ink);
  padding: 0.5rem;
  font-size: 0.85rem;
  cursor: pointer;
}

.segmented button[aria-pressed='true'] {
  background: var(--reader-accent);
  color: #fff;
}

/* ------------------------------------------------------------------ *
 * 书库 — the mount, as a browsing page over a file manager
 *
 * The one screen that shows the mount rather than the catalog. It has two halves —
 * a grid of the books in a folder, and the file rows — and they share a breadcrumb, a
 * folder, a page and a route. So its job is to stay out of the way: a path you can
 * read at the top, a grid or rows that navigate below it, and the destructive actions
 * behind an explicit selection.
 * ------------------------------------------------------------------ */

/*
 * The screen fills the app and scrolls internally, like every other screen.
 * `#app` is `overflow: hidden`, so a screen that does not claim `min-height: 0`
 * on the flex chain pushes its own content off the bottom instead of scrolling.
 * `position: relative` is what the dialogs and the selection pill are placed
 * against.
 *
 * `.manager-screen` is the screen's *former* name and is kept as an alias, because
 * the only thing the two names share is this one rule — the row, the pager and the
 * action bar are all still called `.manager-*`, and those names are what the UI
 * review's scenes and selectors reach for. Deleting the alias would be a rename of
 * the wrapper with no reader-visible effect and one more way for a stale selector to
 * silently stop matching.
 */
.library-screen,
.manager-screen {
  position: relative;
  display: flex;
  flex-direction: column;
  flex: 1 1 auto;
  min-height: 0;
}

/*
 * The host of the screen's component tree.
 *
 * The screens are component trees mounted into a container, and the container
 * must not become a layout box of its own: the styles below are written against
 * `.library-screen > .manager-body`, and a wrapper in between would break the
 * `min-height: 0` chain that lets the list scroll instead of pushing the action
 * bar off the bottom of the phone. `display: contents` makes the host vanish for
 * layout purposes and keeps the tree's children exactly where they were.
 */
.library-ui,
.manager-ui {
  display: contents;
}

/* ---- library: the header's two-page switch ---- */

/*
 * 书库 · 浏览 — the shop.
 *
 * Everything here exists because this half of the library is a *different kind of
 * page* from the file list beside it, which is what the review's second round asked
 * for (「两者列表显示逻辑不一样」): a shop puts the search at the top, fills the
 * window with covers, and gives each one a single action. The file page puts a
 * breadcrumb at the top and gives each row a menu.
 */

/*
 * The search field, on the shop's own scroller.
 *
 * The field itself is the shelf's control — same pill, same glyph, same 16px — so
 * this rule only says where it sits and how wide it is allowed to be. It is inset by
 * the same token the shelf's is (`--shelf-search-inset`), which is the way two screens
 * keep their one shared control looking like one control.
 *
 * It is *not* capped at `--shelf-measure`: the shop's grid is uncapped (see below),
 * and a search field that stopped growing while the covers beside it kept going would
 * be the row that disagrees with the page.
 */
.library-search {
  max-width: none;
  /*
   * The same gutter the shelf's field has, and *only* that: the field is as wide as
   * the page, so there is no measure to subtract and no second inset to add. The
   * covers below use the same token through their padding (see `.library-browse-grid`),
   * which is what makes the field and the grid share a column.
   */
  padding-inline: var(--shelf-search-inset);
  box-sizing: border-box;
  margin: calc(var(--shelf-search-inset) + 0.4rem) 0;
}

/*
 * …and the panels that hang off the row are placed against the *input*, not the row.
 *
 * The magnifier and the clear button are `position: absolute` against this box, which
 * resolves against its *padding box* — so a row with a 0.75rem gutter would put both of
 * them in the gutter, i.e. the glyph would float in the margin and the clear button
 * would sit on top of the cover beside it. Their own offsets are therefore the field's
 * border plus the row's padding, which is one number rather than a coincidence.
 */
.library-search .search-glyph {
  inset-inline-start: calc(var(--shelf-search-inset) + 0.7rem);
}

.library-search .search-clear {
  inset-inline-end: calc(var(--shelf-search-inset) + 0.3rem);
}

/*
 * The covers, laid out as a shop rather than as a shelf.
 *
 * The one difference from `.book-grid` that matters: this grid has **no measure
 * cap**. The shelf caps its width because a shelf is the reader's own collection at a
 * density they chose, and eleven covers across a desktop window is a wall rather than
 * a list. The library is the *server's* folder: its size is a fact about the disk, and
 * a reader browsing it on a wide screen wants more of it visible, not more margin. So
 * the columns are `auto-fill` with no maximum, and growing the window shows more books.
 *
 * The padding is the file listing's own gutter plus the search inset, because the
 * field above and the covers below it share the column and have to line up.
 */
/*
 * The covers' own gutters, and they are *wider* than the field's by the page's own
 * padding: the field is the one control that spans the full content box (it is a
 * single row, and a search box narrower than the list it filters reads as decoration),
 * while the covers keep the page gutter they share with every other grid. The
 * difference is the point of the check below — the field must be inset from the
 * covers, not aligned with them.
 */
.library-browse-grid {
  padding: 0.25rem calc(0.9rem + var(--shelf-search-inset)) 0.75rem;
}

/*
 * …and the covers themselves get the shop's own size ladder.
 *
 * The shelf's ladder is tuned for a *capped* column, and the cap is what keeps it
 * from producing eleven covers a row. With the cap removed (this grid has none — see
 * above) the same minimum would tile a 1600px window with covers 130px wide, which is
 * the failure the ladder exists to prevent and would come back the moment the two
 * grids stop sharing a width rule. So the shop's minimums are the next step up, and
 * they keep climbing with the window: more of the folder on screen, and every cover
 * still big enough to read a title on.
 */
.library-browse-grid[data-density='compact'] {
  --shelf-cover-min: 6.5rem;
}

.library-browse-grid[data-density='comfortable'] {
  --shelf-cover-min: 11rem;
}

@media (min-width: 40rem) {
  .library-browse-grid {
    --shelf-cover-min: 10.5rem;
  }

  .library-browse-grid[data-density='compact'] {
    --shelf-cover-min: 8rem;
  }

  .library-browse-grid[data-density='comfortable'] {
    --shelf-cover-min: 13rem;
  }
}

@media (min-width: 72rem) {
  /*
   * Past the shelf's own measure the shop keeps adding columns instead of margin,
   * because there is nothing to cap to: the covers are already at a readable size
   * and the folder is genuinely large. This is the one place in the product where a
   * wider window shows *more*, and it is the point of an uncapped grid.
   */
  .library-browse-grid {
    --shelf-cover-min: 11.5rem;
  }
}

/*
 * The one line above the grid, when there is something to say about it.
 *
 * `:empty` rather than a `hidden` attribute, because the component decides the
 * sentence and an empty one should cost no space at all: a blank 18px row above a
 * grid of covers is a gap the reader reads as a rendering mistake.
 */
.library-preview-hint {
  padding: 0.5rem calc(0.9rem + var(--shelf-search-inset)) 0;
  font-size: 0.75rem;
  line-height: 1.4;
}

.library-preview-hint:empty {
  display: none;
}

/*
 * A preview card: the shelf's card, with a *second* control on it.
 *
 * The card was a `<button>` on the shelf, and it cannot be one here — a button
 * inside a button is invalid, and the browser fixes it by hoisting the inner one
 * out of the outer, which puts the shelve control somewhere else on the page. So
 * the open target is an inner button and the card is a plain box that positions it.
 *
 * `position: relative` is what the shelve control is placed against, and the control
 * sits at the cover's *bottom-left*, opposite the format badge: the two would
 * otherwise overlap on a compact cover, and the badge is the quieter of the two so
 * it is the one that keeps its corner.
 */
.book-card.is-row {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

/*
 * 加入书架, on the cover of a book that is not on the shelf.
 *
 * A pill over the artwork rather than a row under the title: the row under the title
 * is where the author lives, and a control that appears and disappears there would
 * make one card in a row taller than its neighbours — which is the ragged baseline
 * the grid's two-line title exists to prevent. Over the cover it costs nothing, and
 * it is on the artwork the reader is already looking at.
 *
 * It is *absent* rather than disabled for a book that is already shelved: a control
 * that can only be pressed to no effect is a control the reader learns to distrust,
 * and "this one is mine already" is not a state that needs saying on every card.
 */
.book-card .book-shelve {
  position: absolute;
  inset-block-start: 0.3rem;
  inset-inline-start: 0.3rem;
  display: inline-flex;
  align-items: center;
  gap: 0.15rem;
  border: 0;
  border-radius: 999px;
  padding: 0.15rem 0.4rem;
  background: color-mix(in srgb, var(--reader-accent) 92%, transparent);
  color: #fff;
  font-size: 0.6rem;
  font-family: inherit;
  line-height: 1.5;
  backdrop-filter: blur(4px);
  box-shadow: 0 1px 3px rgb(0 0 0 / 0.25);
  cursor: pointer;
  touch-action: manipulation;
}

.book-card .book-shelve .icon {
  font-size: 0.7rem;
}

.manager-crumbs {
  flex: 1 1 auto;
  display: flex;
  align-items: center;
  gap: 0.15rem;
  overflow-x: auto;
  scrollbar-width: none;
  min-width: 0;
}

.manager-crumbs::-webkit-scrollbar {
  display: none;
}

.manager-crumb {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--reader-ink);
  font-size: 0.9rem;
  font-family: inherit;
  padding: 0.35rem 0.25rem;
  white-space: nowrap;
  cursor: pointer;
}

.manager-crumb[aria-current='true'] {
  font-weight: 600;
}

.manager-crumb-sep {
  color: var(--reader-muted);
}

.manager-body {
  flex: 1 1 auto;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  min-height: 0;
}

.manager-list {
  padding: 0;
}

.manager-row {
  display: grid;
  grid-template-columns: auto 1fr auto auto;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 0.75rem;
  /*
   * Rows are separated by a *hairline*, and the last one has none.
   *
   * A divider under the final row of a list draws a line between the content and
   * nothing, which reads as "there is more, scrolled off" — the exact opposite of
   * what the end of a directory means. `:last-child` rather than a class because
   * every list here is rendered from an array and the end of it is the end of it.
   */
  border-bottom: 1px solid color-mix(in srgb, var(--reader-line) 75%, transparent);
  cursor: pointer;
  touch-action: pan-y;
}

.manager-row:last-child {
  border-bottom: 0;
}

.manager-row:active {
  background: color-mix(in srgb, var(--reader-ink) 6%, transparent);
}

.manager-row[data-selected='true'] {
  background: color-mix(in srgb, var(--reader-accent) 14%, transparent);
}

/*
 * The checkbox is always laid out and only made visible in selection mode.
 *
 * Toggling `display` instead would shift every row's indent the moment a
 * selection begins, which reads as the list jumping under the finger that just
 * started the selection.
 *
 * A *circle* with a drawn tick rather than a square with a filled box: the tick is
 * what says "this one is in", and it is the one part of the control that has to be
 * readable at 20px against an accent fill. `::after` rather than an inline glyph so
 * it scales with the box instead of with the font the row happens to inherit.
 */
.manager-check {
  position: relative;
  width: 1.25rem;
  height: 1.25rem;
  border-radius: 50%;
  border: 1.5px solid color-mix(in srgb, var(--reader-muted) 55%, transparent);
  box-sizing: border-box;
  /* Always laid out, only visible while something is selected: toggling
     `display` would shift every row's indent the moment a selection begins,
     which reads as the list jumping under the finger that started it. */
  opacity: 0;
}

.manager-row[data-selected] .manager-check {
  opacity: 1;
}

.manager-row[data-selected='true'] .manager-check {
  border-color: var(--reader-accent);
  background: var(--reader-accent);
}

/*
 * The tick: two borders on a rotated box.
 *
 * Not a glyph from the icon font, because the font is an *application* typeface and
 * applying it inside a row that is 20px tall would mean managing two font sizes in
 * one control. Not an SVG either, for the same reason the rest of this file is not:
 * one shape is not a set, and a set of one has no consistency to enforce.
 */
.manager-check::after {
  content: '';
  position: absolute;
  inset: 0;
  margin: auto;
  width: 0.28rem;
  height: 0.52rem;
  border: solid #fff;
  border-width: 0 1.5px 1.5px 0;
  transform: translateY(-0.05rem) rotate(45deg);
  opacity: 0;
}

.manager-row[data-selected='true'] .manager-check::after {
  opacity: 1;
}

.manager-name {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  min-width: 0;
}

/*
 * A folder and a file, told apart by more than their outline.
 *
 * `folder` and `file-lines` are the same weight and the same 24-unit grid, so in a
 * single column they read as the same kind of thing — which is a real problem in a
 * list whose primary gesture *is* "this one opens, that one does not". The folder
 * takes the accent and the file stays ink: colour is the fastest thing in the row to
 * scan, and it costs nothing that the name beside it does not already say out loud.
 */
.manager-row[data-type='dir'] .manager-icon {
  color: var(--reader-accent);
}

.manager-icon {
  font-size: 1rem;
  flex: 0 0 auto;
  /*
   * The row's label is a single line of 0.9rem text in a flex box that centres its
   * items, so the icon's box centre and the label's box centre already coincide;
   * `.icon`'s `-0.02em` then puts the *ink* on that same line. Nothing to override —
   * this comment is here because the rule looks like it should need one.
   */
}

.manager-label {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 0.9rem;
}

.manager-meta {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.72rem;
  white-space: nowrap;
}

.manager-badge {
  border: 1px solid color-mix(in srgb, var(--reader-line) 90%, transparent);
  border-radius: 999px;
  padding: 0.02rem 0.35rem;
  font-size: 0.62rem;
  letter-spacing: 0.01em;
  color: var(--reader-muted);
  background: color-mix(in srgb, var(--reader-ink) 3%, transparent);
}

/* The badge a reader needs to see is the one explaining a missing book. */
.manager-badge.warn {
  border-color: color-mix(in srgb, var(--reader-accent) 60%, transparent);
  color: var(--reader-accent);
}

/*
 * "不在书架" — the exception mark.
 *
 * Filled rather than outlined, and in the accent colour, because it is the one
 * badge in the row that means "you are looking at the reason this book is missing
 * from your shelf". The `warn` style is an outline with accent text and is the
 * other explainer badge; this one is solid so the two are distinguishable at a
 * glance in a list where both can appear.
 */
.manager-badge.off {
  border-color: transparent;
  background: color-mix(in srgb, var(--reader-accent) 16%, transparent);
  color: var(--reader-accent);
}

.manager-more {
  width: 2rem;
  height: 2rem;
  font-size: 1.1rem;
  /*
   * It is an `.icon-button`, so it is already inline-grid and already centred; this
   * only has to state where in the row it sits. Left to `baseline`, the button's
   * own baseline — the baseline of the glyph — decides its position, and a glyph box
   * aligned by its baseline is the misalignment this whole change is about.
   */
  vertical-align: middle;
  align-self: center;
}

/*
 * On a read-only mount the row menu offers nothing but "选择", so it is dimmed
 * rather than removed: the row still has to line up with the others, and a
 * column that appears and disappears with the deployment reads as a bug.
 */
/* The read-only dimming, on the screen element the library actually uses. The
   `.manager-screen` alias above is kept only for the base layout rule, which the two
   names share; a state selector belongs to the screen, not to the alias. */
.library-screen[data-writable='false'] .manager-more {
  opacity: 0.35;
}

/*
 * The counts sit *inside* the scroller, not after it.
 *
 * Pinned below a scrolling list they were the first thing pushed off-screen by a
 * directory of forty files — which is exactly when a reader wants to know how
 * many there are, and exactly when "删除完成" would have gone unread.
 */
.manager-status {
  position: sticky;
  inset-block-end: 0;
  font-size: 0.75rem;
  text-align: center;
  padding: 0.5rem 0.75rem;
  background: color-mix(in srgb, var(--reader-surface) 92%, transparent);
  backdrop-filter: blur(6px);
  border-top: 1px solid transparent;
}

.manager-status:not(:empty) {
  border-top-color: var(--reader-line);
}

/*
 * The batch bar scrolls horizontally rather than wrapping or squeezing.
 *
 * Five actions do not fit across a phone, and neither alternative works: wrapping
 * makes the bar two rows tall and pushes the list up under the thumb that is
 * mid-scroll, and `flex: 1` per button shrinks 移动到… to an ellipsis that no
 * longer says what it does. A scrolling row keeps every label readable and the
 * destructive action — deliberately last, so it is never the thing under the
 * finger that just opened the bar — stays off screen until it is looked for.
 */
.manager-actions {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  padding: 0.6rem 0.75rem;
  padding-bottom: calc(0.6rem + env(safe-area-inset-bottom));
  border-top: 1px solid var(--reader-line);
  background: var(--reader-surface);
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

.manager-actions::-webkit-scrollbar {
  display: none;
}

.manager-actions[hidden] {
  display: none;
}

.manager-actions .button {
  /* `flex: 0 0 auto`, so a label is never truncated — the bar scrolls instead. */
  flex: 0 0 auto;
  white-space: nowrap;
}

.manager-selection {
  position: absolute;
  inset-block-start: calc(env(safe-area-inset-top) + 0.25rem);
  inset-inline-start: 50%;
  transform: translateX(-50%);
  background: var(--reader-ink);
  color: var(--reader-paper);
  border-radius: 999px;
  padding: 0.2rem 0.7rem;
  font-size: 0.72rem;
  pointer-events: none;
  z-index: 25;
}

.manager-selection[hidden] {
  display: none;
}

.button.danger {
  border-color: color-mix(in srgb, #c0392b 55%, transparent);
  color: #c0392b;
}

/* ---- dialogs ---- */

.dialog-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  display: grid;
  place-items: center;
  padding: 1rem;
  z-index: 30;
}

.dialog {
  background: var(--reader-surface);
  color: var(--reader-ink);
  border: 1px solid var(--reader-line);
  border-radius: var(--reader-radius);
  padding: 1rem;
  width: min(24rem, 100%);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.dialog h3 {
  margin: 0;
  font-size: 1rem;
}

.dialog p {
  margin: 0;
  font-size: 0.82rem;
  line-height: 1.5;
}

.dialog input {
  appearance: none;
  border: 1px solid var(--reader-line);
  background: var(--reader-paper);
  color: var(--reader-ink);
  border-radius: var(--reader-radius);
  padding: 0.6rem 0.7rem;
  /* 16px, so iOS does not zoom the page on focus and leave the dialog off-screen. */
  font-size: 16px;
  font-family: inherit;
  width: 100%;
}

.dialog-actions {
  display: flex;
  gap: 0.5rem;
  justify-content: flex-end;
}

.dialog-actions .button {
  flex: 0 1 auto;
  min-width: 5rem;
}

.dialog-list {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

/* ---- batch metadata ---- */

/*
 * The batch dialog has seven optional fields, which do not fit on a phone.
 *
 * The fields scroll and the buttons do not. Scrolling the whole dialog instead
 * puts 保存 below the fold, so the reader fills the form, sees no way to commit
 * it, and has to work out that the sheet itself moves — and the on-screen
 * keyboard takes another third of the height while they are typing in it.
 *
 * `max-height` on the *fields* rather than on the dialog also keeps the title
 * visible, so it stays obvious what is being edited after a scroll.
 */
.dialog:has(.dialog-field) {
  max-height: min(86vh, 40rem);
  overflow: hidden;
}

.dialog:has(.dialog-field) .dialog-fields {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  overflow-y: auto;
  min-height: 0;
  /* Room for the last field's label, so it is not flush against the buttons. */
  padding-bottom: 0.2rem;
}

.dialog-field {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.78rem;
  color: var(--reader-muted);
}

.dialog-field input {
  appearance: none;
  border: 1px solid var(--reader-line);
  background: var(--reader-paper);
  color: var(--reader-ink);
  border-radius: var(--reader-radius);
  padding: 0.5rem 0.6rem;
  /* 16px, so iOS does not zoom the page on focus and push the dialog off-screen. */
  font-size: 16px;
  font-family: inherit;
  width: 100%;
}

/*
 * The file input is the trigger for the ⬆ button and is never shown.
 *
 * `display: none` rather than `position: absolute` off-screen: a control that is
 * laid out still takes a tab stop, and this one has no meaning of its own — the
 * button beside it is what the user operates.
 */
.manager-upload-input {
  display: none;
}

/* ---- reduced motion ---- */

/*
 * Honouring `prefers-reduced-motion` in one rule.
 *
 * The alternative — a media query per animated rule — guarantees that the next
 * animation added is the one that ignores the preference. Collapsing the *duration
 * tokens* here means every rule that uses them (which is now all of them) is covered
 * by construction, and a rule that hard-codes its own duration is the visible
 * exception rather than the invisible one.
 *
 * `!important` is unavoidable and appropriate: this is a user preference, and a
 * preference has to beat specificity rather than be outranked by a later rule.
 */
@media (prefers-reduced-motion: reduce) {
  :root {
    --motion-duration: 0.001s;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.001s !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001s !important;
    scroll-behavior: auto !important;
  }
}
/* Source management shares the reader's type and colour tokens. */
.sources-screen { display:flex; flex-direction:column; min-height:0; height:100%; flex:1; }
.sources-header { display:flex; align-items:center; gap:1rem; padding:1rem; border-bottom:1px solid var(--reader-line); }
.sources-header h1 { font-size:1.25rem; flex:1; margin:0; }
.sources-tabs { display:flex; flex-wrap:wrap; gap:.5rem; padding:.75rem 1rem; }
.sources-body { overflow:auto; padding:0 1rem 2rem; flex:1; }
.sources-card { max-width:64rem; margin:0 auto 1rem; padding:1rem; border:1px solid var(--reader-line); border-radius:1rem; }
.sources-card h2 { margin:.25rem 0 1rem; font-size:1.1rem; }
.sources-card label { display:flex; flex-direction:column; gap:.4rem; margin:.75rem 0; }
.sources-card input:not([type=checkbox]), .sources-card select, .sources-card textarea { width:100%; box-sizing:border-box; padding:.65rem; border:1px solid var(--reader-line); border-radius:.5rem; background:var(--reader-surface); color:inherit; font:inherit; }
.sources-card textarea { min-height:6rem; }
.sources-row { display:flex; flex-wrap:wrap; gap:1rem; align-items:center; justify-content:space-between; padding:1rem 0; border-top:1px solid var(--reader-line); }
.sources-row > div:first-child { flex:1 1 15rem; min-width:0; overflow-wrap:anywhere; }
.sources-row small { display:block; margin-top:.35rem; opacity:.75; }
.sources-actions { display:flex; flex-wrap:wrap; gap:.5rem; align-items:center; }
.sources-actions label { margin:0; }
.sources-card .sources-consent { flex-direction:row; align-items:center; }
.sources-search { display:flex; flex-wrap:wrap; align-items:end; gap:.85rem; margin:1rem 0 1.5rem; }
.sources-search label { flex:1 1 10rem; min-width:0; margin:0; font-size:.85rem; color:var(--reader-muted); }
.sources-search .source-keyword { flex:2 1 18rem; }
.sources-search button { display:inline-flex; align-items:center; justify-content:center; min-height:44px; gap:.5rem; }
.sources-search input, .sources-search select { min-height:44px; color:var(--reader-ink); }
.catalog-feedback { margin:1rem 0; padding-top:1.25rem; border-top:1px solid var(--reader-line); }
.search-progress { display:flex; flex-wrap:wrap; align-items:center; gap:.6rem 1rem; padding:1rem; border-radius:.75rem; background:color-mix(in srgb,var(--reader-accent) 6%,var(--reader-paper)); font-size:.9rem; }
.search-progress progress { width:10rem; max-width:100%; height:.45rem; accent-color:var(--reader-accent); }
.search-progress small { color:var(--reader-muted); }
.search-stop { border-color:var(--reader-accent); }
.search-split { display:flex; position:relative; flex:none; }
.search-split > .primary:first-child { border-radius:var(--reader-radius, .75rem) 0 0 var(--reader-radius, .75rem); }
.search-split > .primary:only-child { border-radius:var(--reader-radius, .75rem); }
.search-split .search-menu-toggle { border-radius:0 var(--reader-radius, .75rem) var(--reader-radius, .75rem) 0; padding-inline:.65rem; border-left:1px solid var(--reader-line); }
.search-menu-toggle .icon { transform:rotate(90deg); }
.search-menu { position:absolute; right:0; top:calc(100% + .45rem); z-index:5; width:min(17rem, calc(100vw - 4rem)); padding:.35rem; border:1px solid var(--reader-line); border-radius:.8rem; background:var(--reader-paper); box-shadow:0 8px 24px #0002; }
.search-menu button { display:flex; align-items:center; width:100%; padding:.65rem .75rem; text-align:left; border:0; background:transparent; color:var(--reader-ink); border-radius:.5rem; }
.search-menu button:hover, .search-menu button:focus-visible { background:color-mix(in srgb, var(--reader-accent) 12%, transparent); }
.search-menu small { display:block; margin-top:.2rem; color:var(--reader-muted); font-size:.75rem; }
.catalog-summary { display:flex; flex-wrap:wrap; gap:.5rem 1rem; justify-content:space-between; align-items:center; }
.catalog-summary strong { font-size:1rem; }
.catalog-summary span { display:flex; align-items:center; gap:.4rem; color:var(--reader-muted); font-size:.85rem; }
.catalog-context { color:var(--reader-muted); font-size:.82rem; line-height:1.7; overflow-wrap:anywhere; margin:.4rem 0 .75rem; }
.catalog-errors { padding:.7rem 1rem; border:1px solid var(--reader-line); border-radius:.75rem; background:color-mix(in srgb,var(--reader-muted) 5%,var(--reader-paper)); }
.catalog-errors summary { cursor:pointer; font-size:.85rem; color:var(--reader-muted); }
.catalog-errors summary:focus-visible { outline:2px solid var(--reader-accent); outline-offset:4px; }
.catalog-errors ul { list-style:none; margin:.6rem 0 0; padding:0; }
.catalog-errors li { display:grid; grid-template-columns:minmax(7rem,1fr) minmax(0,3fr) auto; align-items:baseline; gap:.3rem 1rem; padding:.6rem 0; border-top:1px solid var(--reader-line); font-size:.84rem; overflow-wrap:anywhere; }
.catalog-errors li strong { font-weight:500; }
.catalog-errors li p { margin:0; line-height:1.6; color:var(--reader-muted); }
.catalog-errors code { font-size:.7rem; color:var(--reader-muted); }
.catalog-empty { display:flex; flex-direction:column; align-items:center; gap:.8rem; text-align:center; padding:2.5rem 1rem; }
.catalog-empty > .icon { font-size:1.7rem; color:var(--reader-muted); }
.catalog-empty p { margin:0; font-size:.9rem; color:var(--reader-muted); line-height:1.7; }
.catalog-book { padding:1.4rem 0; align-items:flex-start; }
.catalog-book strong { font-size:1.05rem; }
.catalog-book .source-description { line-height:1.75; color:var(--reader-muted); margin:.7rem 0 0; }
.catalog-book .sources-actions { padding-top:.2rem; }
.catalog-pagination { display:flex; justify-content:flex-end; gap:.6rem; padding-top:1rem; border-top:1px solid var(--reader-line); }
@media (max-width: 640px) {
  .catalog-errors li { grid-template-columns:minmax(0,1fr); }
  .sources-search .source-keyword { flex-basis:100%; }
  .sources-search > button { width:100%; }
  .sources-search > .search-split { width:100%; }
  .search-split > .primary:first-child { flex:1; }
}
.source-description { max-height:6rem; overflow:auto; font-size:.9rem; white-space:pre-wrap; }

/* Mobile reading: the surface and its information strip never resize with chrome. */
[data-theme='green'] {
  --reader-ink: #23392c;
  --reader-paper: #d5ecd7;
  --reader-surface: #e8f2e8;
  --reader-muted: #617a65;
  --reader-line: #bdd6bf;
  --reader-accent: #497553;
}
svg.icon { display: inline-block; width: 1em; height: 1em; flex-shrink: 0; vertical-align: middle; }
.reader-screen { --reader-footer-height: calc(8.5rem + var(--safe-bottom)); }
.reader-screen .book-host {
  inset-block-start: calc(1.8rem + var(--safe-top));
  inset-block-end: calc(1.8rem + var(--safe-bottom) + var(--reader-page-trim, 0px));
}
.reading-indicator {
  position: absolute;
  inset-inline: 0;
  padding-inline: max(1.25rem, var(--safe-left)) max(1.25rem, var(--safe-right));
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  color: var(--reader-muted);
  background: var(--reader-paper);
  font-size: 0.72rem;
  line-height: 1.2;
  z-index: var(--reader-layer-readout);
  pointer-events: none;
}
.reading-indicator-top { top: 0; height: calc(1.8rem + var(--safe-top)); padding-top: calc(0.5rem + var(--safe-top)); }
.reading-indicator-bottom { bottom: 0; height: calc(1.8rem + var(--safe-bottom)); padding-top: 0.35rem; padding-bottom: var(--safe-bottom); }
.reading-indicator > span { min-width: 0; flex: 1; overflow: hidden; white-space: nowrap; text-overflow: ellipsis; font-variant-numeric: tabular-nums; }
.indicator-left { text-align: start; }
.indicator-right { text-align: end; }
.reading-indicator > span:empty { flex: 0; }
.reader-screen .topbar {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 0.5rem;
  height: auto;
  min-height: calc(4.5rem + var(--safe-top));
  padding: calc(0.6rem + var(--safe-top)) 1rem 0.6rem;
  background: var(--reader-surface);
  border: 0;
  box-shadow: 0 2px 12px #0000000a;
}
.reader-heading { min-width: 0; display: grid; gap: 0.3rem; }
.reader-heading strong { font-size: 1.05rem; font-weight: 600; }
.reader-heading span { font-size: 0.75rem; color: var(--reader-muted); }
.reader-heading strong, .reader-heading span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.reader-screen .footer {
  height: var(--reader-footer-height);
  padding: 0.5rem 1rem calc(0.4rem + var(--safe-bottom));
  background: var(--reader-surface);
  border: 0;
  box-shadow: 0 -2px 12px #0000000a;
}
.reader-screen .progress-row { display: flex; align-items: center; gap: 0.75rem; padding: 0; min-height: 3rem; }
.reader-screen .nav-chapter { flex: 0 0 auto; font-size: 0.8rem; padding: 0.35rem 0; min-height: 44px; }
.reader-scrub { flex: 1; min-width: 0; display: grid; text-align: center; }
.reader-screen .progress-scrubber { width: 100%; min-height: 28px; margin: 0; }
.reader-screen .progress-page { font-size: 0.65rem; color: var(--reader-muted); }
.reader-actions { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 0.25rem; }
.reader-actions .top-button { min-width: 0; max-width: none; min-height: 60px; padding: 0.45rem 0; gap: 0.45rem; }
.reader-actions .icon { font-size: 1.4rem; }
.reader-actions .top-button-label { font-size: 0.75rem; font-weight: 400; }
.reader-screen .reader-rail {
  top: auto;
  bottom: calc(var(--reader-footer-height) + 1rem);
  left: auto;
  right: max(1rem, var(--safe-right));
  width: auto;
  max-height: none;
  padding: 0;
  transform: none;
  border: none;
  background: transparent;
  box-shadow: none;
}
.reader-screen .rail-button { width: 48px; height: 48px; border-radius: 50%; background: var(--reader-surface); box-shadow: 0 3px 12px #00000020; }
.reader-screen .rail-button .icon { font-size: 1.5rem; }
.reader-screen .panel { border-radius: 20px 20px 0 0; max-height: 62%; background: var(--reader-surface); box-shadow: 0 -6px 30px #00000018; }
.reader-screen .panel-header { padding: 0.5rem 1.25rem 0.75rem; }
.reader-screen .panel-body { padding-inline: 1.25rem; }
.reader-screen .panel .field { padding-block: 0.8rem; }
.reader-screen .panel .tts-bar { position: static; border-radius: 12px; width: auto; transform: none; margin-bottom: 1rem; }
.reader-screen .panel-header > .icon-button { margin-inline-start: auto; }
.reader-screen .panel .field { grid-template-columns: minmax(5.5rem, max-content) minmax(0, 1fr); gap: 0.75rem; padding-block: 0.5rem; }
.reader-screen .field input[type='range'] { min-height: 32px; }
.reader-screen .field input[type='range']::-webkit-slider-runnable-track { height: 4px; border-radius: 2px; background: var(--reader-line); }
.reader-screen .field input[type='range']::-webkit-slider-thumb { appearance: none; width: 18px; height: 18px; margin-top: -7px; border-radius: 50%; background: var(--reader-accent); }
.reader-screen .field input[type='range']::-moz-range-track { height: 4px; border-radius: 2px; background: var(--reader-line); }
.reader-screen .field input[type='range']::-moz-range-thumb { width: 18px; height: 18px; border: 0; border-radius: 50%; background: var(--reader-accent); }

.sources-card h3, .sources-body > p { overflow-wrap:anywhere; }
.sources-card form + form { margin-top:.65rem; }

/* Generic declarative extension pages, scoped to the selected source instance. */
.extension-screen .sources-body { width: 100%; max-width: 64rem; margin-inline: auto; box-sizing: border-box; }
.extension-description { color: var(--muted, #777); margin: 0 0 16px; line-height: 1.6; }
.extension-tabs { display: flex; flex-wrap: nowrap; gap: 4px; min-width: 0; max-width: 100%; overflow-x: auto; overscroll-behavior-x: contain; scrollbar-width: thin; border-bottom: 1px solid var(--border, #ddd); margin-bottom: 20px; }
.extension-tabs button { flex: 0 0 auto; white-space: nowrap; padding: 12px 16px; background: transparent; color: inherit; border: 0; border-bottom: 3px solid transparent; cursor: pointer; font: inherit; }
.extension-tabs button[aria-selected="true"] { border-bottom-color: currentColor; font-weight: 700; }
.extension-tabs button:focus-visible { outline: 2px solid currentColor; outline-offset: -3px; }
.extension-screen h2 { font-size: 1rem; margin: 20px 0 12px; }
.extension-screen h3 { margin: 0 0 8px; }
.extension-item-heading { display: flex; gap: 16px; align-items: start; justify-content: space-between; }
.extension-item-heading > div { min-width: 0; }
.extension-item-heading > button { flex-shrink: 0; }
.extension-item .source-description { margin: 0; overflow-wrap: anywhere; }
.extension-actions:not([hidden]) { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 16px; }
.extension-actions form:has(label) { flex-basis: 100%; }
.extension-screen input:not([type=checkbox]), .extension-screen textarea, .extension-screen select { box-sizing: border-box; max-width: 100%; }
.extension-screen textarea { min-height: 9rem; }
.extension-empty { padding: 28px 16px; text-align: center; color: var(--muted, #777); line-height: 1.7; }

.extension-toolbar { flex: none; width: 100%; max-width: 64rem; margin-inline: auto; padding: 0 1rem; box-sizing: border-box; }
.extension-toolbar .extension-tabs { margin-bottom: .75rem; border-color: var(--reader-line); }
.extension-toolbar .notice { margin: 0 0 .75rem; overflow-wrap: anywhere; }
.extension-description, .extension-empty { color: var(--reader-muted); }
.extension-screen .sources-header h1 { min-width: 0; overflow-wrap: anywhere; }
.extension-form-inline { display: flex; flex-wrap: wrap; align-items: end; gap: .75rem; }
.extension-form-inline h3 { flex-basis: 100%; }
.extension-screen .extension-form-inline label { flex: 1 1 14rem; min-width: 0; margin: 0; }
.extension-screen .extension-form-inline label[data-field-type=number] { flex: 0 1 15rem; }
.extension-screen label[data-field-type=boolean] { flex-direction: row; align-items: center; }
.extension-screen input[type=checkbox] { width: 1.25rem; height: 1.25rem; }
.extension-actions form + form { margin-top: 0; }
.extension-actions .extension-form-inline { border-top: 1px solid var(--reader-line); padding-top: .75rem; }
.extension-confirm { border: 1px solid var(--reader-line); border-radius: .5rem; padding: .75rem; margin-top: .5rem; }
.extension-confirm p { margin: 0 0 .75rem; }
.extension-confirm button + button { margin-inline-start: .5rem; }
.extension-screen button, .source-next-step .button { min-height: 44px; }
.source-catalog, .source-editor { scroll-margin-top: 1rem; }
@media (max-width: 600px) {
  .extension-screen .extension-form-inline label { flex-basis: 100%; }
  .extension-screen .extension-form-inline label[data-field-type=number] { flex: 1 1 9rem; }
  .extension-item-heading { gap: .75rem; }
}
.extension-tabs button:disabled { opacity: .55; cursor: default; }
.extension-output { min-width: 0; }
.extension-output summary { font-weight: 650; cursor: pointer; padding-block: .35rem; }
.extension-output pre { max-height: 26rem; overflow: auto; white-space: pre-wrap; overflow-wrap: anywhere; margin: .75rem 0 0; padding: 1rem; background: var(--reader-surface); border: 1px solid var(--reader-line); border-radius: .5rem; font: .8125rem/1.7 ui-monospace, SFMono-Regular, Consolas, monospace; }
.extension-output pre:focus-visible { outline: 2px solid currentColor; outline-offset: 2px; }

/* Source hub: navigation tabs, one primary action per row, secondary settings on demand. */
.sources-hub .sources-tabs { flex: none; flex-wrap: nowrap; gap: 0; padding: 0 1rem; width: 100%; max-width: 66rem; margin: 0 auto 1rem; }
.sources-hub .sources-tabs [role=tab] { flex: 1; min-width: 0; min-height: 52px; padding: .85rem .35rem; border: 0; border-bottom: 2px solid var(--reader-line); background: transparent; color: var(--reader-muted); font: inherit; cursor: pointer; }
.sources-hub .sources-tabs [aria-selected=true] { color: var(--reader-ink); border-bottom-color: var(--reader-accent); font-weight: 650; }
.sources-hub .sources-tabs [role=tab]:focus-visible, .source-manage-trigger:focus-visible, .source-management-link:focus-visible { outline: var(--focus-ring); outline-offset: -2px; }
.sources-tab-dot { display: inline-block; width: 6px; height: 6px; margin: 0 0 .2rem .35rem; border-radius: 50%; background: var(--reader-accent); }
.sources-list-heading { display: flex; align-items: center; justify-content: space-between; gap: .75rem; margin-bottom: .5rem; }
.sources-list-heading h2 { margin: 0; }
.source-count { margin-inline-start: .3rem; font-size: .8rem; color: var(--reader-muted); font-weight: 400; }
.source-add { display: inline-flex; align-items: center; gap: .3rem; min-height: 44px; padding: .5rem .7rem; }
.sources-list .source-entry { display: block; padding: 1rem 0; }
.sources-list .source-entry:last-child { padding-bottom: 0; }
.source-entry-top { display: flex; align-items: center; gap: 1rem; }
.source-entry-info { flex: 1; min-width: 0; }
.source-entry-info strong { display: block; line-height: 1.5; }
.source-entry-info small { font-size: .8rem; color: var(--reader-muted); opacity: 1; }
.source-state { display: inline-block; font-size: .72rem; color: var(--reader-muted); margin-top: .5rem; }
.source-state::before { content: ''; display: inline-block; height: 5px; width: 5px; border-radius: 50%; background: currentColor; vertical-align: middle; margin-right: .35rem; }
.source-state.is-enabled { color: var(--reader-accent); }
.source-entry-actions { display: flex; align-items: center; gap: .6rem; flex-shrink: 0; }
.source-manage-trigger { display: inline-flex; align-items: center; justify-content: center; gap: .25rem; min-height: 44px; padding: .4rem; border: 0; background: transparent; font: inherit; font-size: .85rem; color: var(--reader-muted); cursor: pointer; }
.source-manage-trigger[aria-expanded=true] .icon { transform: rotate(90deg); }
.source-management { display: flex; flex-wrap: wrap; align-items: center; gap: .25rem 1rem; margin-top: .85rem; padding: .5rem .75rem; border-radius: .6rem; background: color-mix(in srgb, var(--reader-ink) 4%, transparent); }
.source-management-link { display: inline-flex; align-items: center; justify-content: space-between; gap: .5rem; min-height: 44px; padding: .5rem 0; border: 0; background: transparent; color: var(--reader-ink); font: inherit; font-size: .85rem; text-decoration: none; cursor: pointer; }
.source-management-link:disabled, .source-manage-trigger:disabled, .sources-hub [role=tab]:disabled { opacity: .5; cursor: default; }
.source-toggle { color: var(--reader-muted); }
.sources-hub .sources-tabs [role=tab] { font-size: .9rem; }
.source-picker label { max-width: 32rem; }
@media (min-width: 768px) {
  .source-picker { display:flex; align-items:center; flex-wrap:wrap; gap:1rem 2rem; }
  .source-picker > div { flex:1; }
  .source-picker > div h2 { margin:0 0 .35rem; }
  .source-picker > div p { margin:0; font-size:.85rem; }
  .source-picker > label { flex:1; margin:0; font-size:.85rem; color:var(--reader-muted); }
  .source-picker > p { flex-basis:100%; margin:0; }
}
.source-modal { color: var(--reader-ink); background: var(--reader-paper); border: 1px solid var(--reader-line); border-radius: 1rem; padding: 0; width: min(36rem, calc(100% - 2rem)); max-height: calc(100dvh - 2rem); overflow: hidden; }
.source-modal[open] { display: flex; flex-direction: column; }
.source-modal::backdrop { background: #0007; }
.source-modal-header { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: .75rem 1rem; border-bottom: 1px solid var(--reader-line); flex: none; }
.source-modal-header h2 { margin: 0; font-size: 1.15rem; }
.source-modal-form.sources-card { display: flex; flex-direction: column; margin: 0; border: 0; padding: 0; width: 100%; min-height: 0; overflow: hidden; }
.source-modal-content { overflow-y: auto; overscroll-behavior: contain; padding: 0 1rem 1rem; }
.source-modal-actions { display: flex; flex-wrap: wrap; gap: .5rem; padding: .75rem 1rem; border-top: 1px solid var(--reader-line); flex: none; }
.source-modal-actions button { min-height: 44px; }

/* Collection pages share a quiet heading, labelled destinations and useful empty states. */
.shelf-head { align-items: center; padding-top: calc(1.25rem + var(--safe-top)); padding-bottom: .85rem; }
.shelf-head-actions { margin-top: 0; }
.shelf-head .icon-button, .collection-heading .icon-button { width: 44px; height: 44px; border-radius: .8rem; }
.shelf-subtitle { margin-top: .45rem; line-height: 1.5; }
.collection-header { padding: calc(1.25rem + var(--safe-top)) calc(.9rem + var(--safe-right)) .75rem calc(.9rem + var(--safe-left)); flex: none; }
.collection-heading { display: flex; align-items: center; gap: .5rem; }
.collection-heading-text { flex: 1; min-width: 0; }
.collection-heading h1 { margin: 0; font-size: 1.5rem; font-weight: 650; letter-spacing: -.02em; line-height: 1.15; }
.collection-heading p { margin: .45rem 0 0; font-size: .78rem; line-height: 1.5; }
.collection-links { display: flex; gap: .65rem; margin-top: .85rem; }
.shelf-links { max-width: calc(var(--shelf-measure) - 1.8rem); margin: 0 auto .9rem; padding-inline: calc(.9rem + var(--safe-left)) calc(.9rem + var(--safe-right)); }
.collection-link.button { display: flex; align-items: center; gap: .6rem; flex: 1; min-width: 0; min-height: 48px; padding: .7rem .85rem; font-size: .875rem; border-radius: .8rem; background: color-mix(in srgb, var(--reader-accent) 4%, var(--reader-paper)); border-color: color-mix(in srgb, var(--reader-line) 65%, transparent); text-align: start; }
.collection-link > span { flex: 1; }
.collection-link[hidden] { display: none; }
.collection-link > .icon:first-child { color: var(--reader-accent); }
.collection-link > .icon:last-child { color: var(--reader-muted); font-size: .8rem; }
.shelf-screen .shelf-search input, .library-search input { border-radius: .85rem; min-height: 48px; }
.library-browse-screen .library-search { margin-top: .35rem; }
.library-path { margin-top: .75rem; padding: .25rem 0 0; }
.library-path .manager-crumb { min-height: 44px; }
.collection-empty.empty-state { width: calc(100% - 2rem); max-width: 30rem; margin: clamp(1.5rem, 7vh, 4rem) auto 2rem; padding: 1.75rem 1.25rem; gap: .7rem; border: 1px solid var(--reader-line); border-radius: 1.25rem; background: color-mix(in srgb, var(--reader-surface) 45%, var(--reader-paper)); }
.collection-empty .empty-glyph { box-sizing: content-box; width: 30px; height: 30px; padding: 1rem; border-radius: 1.1rem; background: color-mix(in srgb, var(--reader-accent) 9%, transparent); color: var(--reader-accent); opacity: 1; margin-bottom: .5rem; }
.collection-empty p { font-size: 1.1rem; line-height: 1.5; }
.collection-empty p.muted { max-width: 23rem; font-size: .875rem; line-height: 1.8; text-wrap: pretty; }
.collection-empty .empty-actions { margin-top: .6rem; gap: .65rem; }
.collection-empty .button { min-height: 44px; font-size: .875rem; }
.library-browse-body > .manager-status { background: transparent; border: 0; margin: .75rem auto; }
.file-manager-header .manager-crumbs { margin-top: .75rem; padding: .25rem 0; }
.file-manager-header .manager-crumb { min-height: 44px; }
.library-files-screen .manager-list { margin: .5rem 1rem; border: 1px solid var(--reader-line); border-radius: 1rem; overflow: hidden; }
.library-files-screen .manager-row { grid-template-columns: 24px minmax(0, 1fr) 44px; gap: .4rem .65rem; padding: .9rem .75rem; }
.library-files-screen .manager-check { grid-column: 1; grid-row: 1 / 3; }
.library-files-screen .manager-name { grid-column: 2; grid-row: 1; }
.library-files-screen .manager-label { white-space: normal; overflow-wrap: anywhere; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; line-height: 1.5; }
.library-files-screen .manager-meta { grid-column: 2; grid-row: 2; flex-wrap: wrap; gap: .3rem .65rem; white-space: normal; padding-left: 1.5rem; }
.library-files-screen .manager-more { grid-column: 3; grid-row: 1 / 3; width: 44px; height: 44px; }
.library-files-screen .manager-status { position: static; border: 0; background: transparent; padding: .5rem 1rem 1rem; }
.shelf-settings.panel { position: fixed; }
.shelf-settings .panel-header { padding: .75rem 1rem; flex: none; }
.shelf-settings .panel-header h2 { flex: 1; }
.shelf-settings .panel-header > .icon-button { flex: none; margin-inline-start: auto; width: 44px; height: 44px; }
.shelf-settings .panel-body { padding-top: 0; }
.shelf-settings .section-title:first-child { margin-top: 0; }
.shelf-discovery { display: contents; }
.plugin-install { margin-block: 1rem 1.5rem; border: 1px solid var(--reader-line); border-radius: .85rem; overflow: hidden; }
.plugin-install-tabs { display: flex; border-bottom: 1px solid var(--reader-line); }
.plugin-install-tabs button { flex: 1; min-height: 44px; padding: .75rem; border: 0; border-bottom: 2px solid transparent; background: transparent; color: var(--reader-muted); font: inherit; cursor: pointer; }
.plugin-install-tabs button[aria-selected=true] { border-bottom-color: var(--reader-accent); color: var(--reader-ink); font-weight: 600; }
.plugin-install form { display: flex; flex-direction: column; gap: .85rem; padding: 1.25rem; margin: 0; min-width: 0; }
.plugin-install form[hidden] { display: none; }
.plugin-install small { color: var(--reader-muted); line-height: 1.5; }
.plugin-install input { width: 100%; min-width: 0; box-sizing: border-box; }
.plugin-install input[type=file] { padding: .5rem; }
.plugin-install .button { align-self: flex-start; }
/* Desktop keeps navigation compact and settings beside the collection. */
@media (min-width: 64rem) {
  .shelf { --shelf-measure: var(--collection-measure); }
  .shelf-head, .shelf-discovery, .shelf-section { width: calc(100% - 3rem); }
  .shelf-head { padding-top: 2rem; padding-bottom: 1.25rem; }
  .shelf-discovery { display: flex; align-items: center; gap: 1.5rem; max-width: var(--shelf-measure); margin: 0 auto 1rem; padding-inline: .9rem; }
  .shelf-discovery .shelf-links { flex: none; margin: 0; padding: 0; }
  .shelf-discovery .shelf-search { flex: 1; max-width: 36rem; margin: 0 0 0 auto; }
  .collection-link.button { flex: none; min-width: 9rem; min-height: 44px; }
  .collection-header { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; gap: .5rem 2rem; padding-top: 2rem; }
  .collection-header .collection-links { margin-top: 0; }
  .collection-header .manager-crumbs { grid-column: 1 / -1; }
  .collection-header, .library-browse-body, .library-files-screen .manager-body { width: calc(100% - 3rem); max-width: var(--collection-measure); margin-inline: auto; }
  .library-files-screen .manager-row { grid-template-columns: 24px minmax(0, 1fr) minmax(15rem, 22rem) 44px; min-height: 64px; padding-block: .5rem; }
  .library-files-screen .manager-check { grid-row: 1; }
  .library-files-screen .manager-meta { grid-column: 3; grid-row: 1; justify-content: flex-end; padding-left: 0; }
  .library-files-screen .manager-more { grid-column: 4; grid-row: 1; }
  .shelf-settings.panel { inset: 1rem 1rem auto auto; width: 26rem; height: min(42rem, calc(100dvh - 2rem)); max-height: calc(100dvh - 2rem); border: 1px solid var(--reader-line); border-radius: 1rem; box-shadow: 0 12px 48px #0003; overflow: hidden; animation-name: shelf-settings-in; }
  .shelf-settings .switch-field { grid-template-columns: minmax(0, 1fr) auto; }
  .sources-header { width: calc(100% - 3rem); max-width: var(--collection-measure); margin-inline: auto; padding: 2rem .9rem .75rem; border-bottom: 0; }
  .sources-header h1 { font-size: 1.5rem; font-weight: 650; }
  .sources-hub .sources-tabs [role=tab] { flex: 0 1 auto; min-width: 9rem; padding-inline: 1.5rem; }
  .extension-tabs button { min-width: 7rem; padding-inline: 1.5rem; }
  .sources-hub .sources-body, .extension-screen .sources-body, .sources-hub .sources-tabs, .extension-toolbar { width: calc(100% - 3rem); max-width: var(--collection-measure); margin-inline: auto; padding-inline: .9rem; }
  .sources-body .sources-card { max-width: none; }
  .reader-screen { --reader-footer-height: 5.5rem; }
  .reader-screen { --desktop-page-width: 52rem; }
  .reader-screen .stage { background: color-mix(in srgb, var(--reader-paper) 95%, var(--reader-ink)); }
  .reader-screen .stage::before { content: ''; position: absolute; inset: 0; width: var(--desktop-page-width); max-width: 100%; margin-inline: auto; background: var(--reader-paper); border-inline: 1px solid var(--reader-line); box-shadow: 0 0 40px #00000005; pointer-events: none; }
  .reader-screen .book-host[data-layout='reflowable'] { width: var(--desktop-page-width); max-width: 100%; margin-inline: auto; }
  .reader-screen .topbar { inset-inline: 2rem; width: calc(100% - 4rem); max-width: var(--desktop-page-width); min-height: 4.5rem; margin-inline: auto; padding-inline: 1.5rem; border-bottom: 1px solid var(--reader-line); background: var(--reader-paper); box-shadow: none; }
  .reader-screen .topbar .reader-heading strong { font-size: 1rem; }
  .reader-screen .topbar .reader-heading span { font-size: .72rem; }
  .reader-screen .footer { display: flex; align-items: center; gap: 1rem; inset-inline: 2rem; bottom: 1.5rem; width: calc(100% - 4rem); max-width: 50rem; height: 4.5rem; margin-inline: auto; padding: .55rem 1rem; border: 1px solid var(--reader-line); border-radius: .85rem; background: var(--reader-surface); box-shadow: 0 8px 32px #00000012; }
  .reader-screen .progress-row { flex: 1; min-width: 0; }
  .reader-screen .reader-actions { display: flex; gap: .25rem; padding-left: .75rem; border-left: 1px solid var(--reader-line); }
  .reader-screen .reader-actions .top-button { flex-direction: row; min-width: 4.75rem; min-height: 44px; padding: .5rem .7rem; border-radius: .7rem; }
  .reader-screen .reader-actions .top-button:hover { background: color-mix(in srgb, var(--reader-accent) 10%, transparent); }
  .reader-screen .reader-actions .icon { font-size: 1.1rem; }
  .reader-screen .reader-rail { right: max(1rem, calc((100% - var(--desktop-page-width)) / 2 - 4.5rem)); bottom: 2.25rem; }
  .reader-screen .reading-indicator { width: var(--desktop-page-width); max-width: 100%; margin-inline: auto; padding-inline: 1.5rem; font-size: .75rem; }
  .reader-screen .scrim { background: color-mix(in srgb, var(--reader-ink) 12%, transparent); }
  .reader-screen .panel { inset: 1rem 1rem 1rem auto; width: 26rem; height: calc(100% - 2rem); max-height: none; border: 1px solid var(--reader-line); border-radius: 1rem; overflow: hidden; animation-name: shelf-settings-in; }
  .reader-screen .panel[data-placement='start'] { inset-inline: 1rem auto; width: 23rem; animation-name: reader-contents-in; }
  .reader-screen .panel-grip { display: none; }
  .reader-screen .panel-header { flex: none; padding: .75rem 1.25rem; }
  .reader-screen .panel-header .icon-button { width: 40px; height: 40px; border-radius: .6rem; }
  .reader-screen .panel .section-title { font-size: .78rem; font-weight: 650; letter-spacing: .05em; color: var(--reader-accent); padding-top: .9rem; padding-bottom: .65rem; }
  .reader-screen .panel-body { padding-top: 0; }
  .reader-screen .section-title:first-child { margin-top: 0; }
}
@keyframes reader-contents-in {
  from { opacity: 0; transform: translateX(-1rem); }
  to { opacity: 1; transform: translateX(0); }
}
@keyframes shelf-settings-in {
  from { opacity: 0; transform: translateX(1rem); }
  to { opacity: 1; transform: translateX(0); }
}
@media (max-width: 600px) {
  .source-entry-actions { flex-direction: column; gap: 0; }
  .source-entry-top { align-items: center; }
  .source-management-link { width: 100%; }
  .source-management-link + .source-management-link { border-top: 1px solid var(--reader-line); }
}

/* Reading source actions share the toolbar; provenance occupies its own compact row. */
.reader-screen .topbar { flex-wrap: wrap; }
.reader-heading { flex: 1; }
.reader-top-actions { display: flex; gap: .25rem; flex: none; margin-inline-start: auto; }
.reader-source-info { flex: 1 0 100%; display: flex; gap: .65rem; align-items: center; min-width: 0; font-size: .7rem; color: var(--reader-muted); border-top: 1px solid var(--reader-line); padding-top: .45rem; }
.reader-source-info span { flex: 0 1 auto; max-width: 35%; overflow: hidden; white-space: nowrap; text-overflow: ellipsis; }
.reader-source-info a { flex: 1; min-width: 0; overflow: hidden; white-space: nowrap; text-overflow: ellipsis; color: inherit; text-decoration: none; }
.reader-source-info a:hover { text-decoration: underline; }
.book-detail { padding-top: 1rem; }
.book-detail h3 { margin: 0; font-size: 1.35rem; overflow-wrap: anywhere; }
.book-detail-author { color: var(--reader-muted); }
.book-detail dl { display: grid; grid-template-columns: auto minmax(0, 1fr); gap: .6rem 1rem; padding-block: .8rem; border-block: 1px solid var(--reader-line); }
.book-detail dt { color: var(--reader-muted); }
.book-detail dd { margin: 0; overflow-wrap: anywhere; }
.book-detail-description { white-space: pre-wrap; line-height: 1.8; overflow-wrap: anywhere; }

.reader-book-heading { padding: 0; border: 0; background: transparent; color: inherit; text-align: start; cursor: pointer; min-height: 44px; }

.alternative-preview { padding-block: 1rem; display: grid; gap: .75rem; }
.alternative-preview h4 { margin: 0; }
.alternative-preview label { display: grid; gap: .5rem; }
.alternative-preview select { width: 100%; min-width: 0; min-height: 44px; }

.catalog-book:has(.catalog-source-count) { display: flex; align-items: center; gap: 1rem; }
.catalog-book:has(.catalog-source-count) > div { flex: 1; min-width: 0; }
.catalog-source-count { display: inline-flex; align-items: center; gap: .5rem; flex: none; min-height: 44px; white-space: nowrap; }
.catalog-source-heading { padding-block: 1rem; border-bottom: 1px solid var(--reader-line); }
.catalog-source-heading h3 { margin: 0; font-size: 1.15rem; overflow-wrap: anywhere; }
.catalog-source-heading p { margin: .4rem 0; color: var(--reader-muted); }
.catalog-source-heading small { color: var(--reader-muted); }
.catalog-source-item { padding-block: 1rem; border-bottom: 1px solid var(--reader-line); }
.catalog-source-item:last-child { border-bottom: 0; }
.catalog-source-item strong { overflow-wrap: anywhere; }
.catalog-source-item .source-description { margin: .4rem 0 .75rem; }
.catalog-source-item .sources-actions { justify-content: flex-end; }

@media (min-width: 600px) {
  .catalog-source-item { display: flex; align-items: center; gap: 1rem; }
  .catalog-source-item > div:first-child { flex: 1; min-width: 0; }
  .catalog-source-item .sources-actions { flex: none; }
  .catalog-source-item .source-description { margin-bottom: 0; }
}
.source-default-badge { display: inline-block; margin-inline-start: .6rem; padding: .12rem .45rem; border-radius: .35rem; background: color-mix(in srgb, var(--reader-accent) 10%, transparent); color: var(--reader-accent); font-size: .7rem; font-weight: 500; vertical-align: middle; }
.source-switch { padding-block: .25rem 1rem; overflow-wrap: anywhere; }
.source-switch-status { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: .65rem; font-size: .85rem; }
.source-switch-status strong { color: var(--reader-accent); font-size: .8rem; font-weight: 500; }
.source-switch-status progress { width: 100%; height: 3px; accent-color: var(--reader-accent); }
.source-switch-hint { margin: .65rem 0 1rem; color: var(--reader-muted); font-size: .75rem; line-height: 1.6; }
.source-switch-list { display: grid; gap: .7rem; }
.source-switch-card { display: flex; flex-direction: column; gap: .55rem; width: 100%; min-width: 0; padding: 1rem; border: 1px solid var(--reader-line); border-radius: .85rem; background: var(--reader-paper); color: var(--reader-ink); text-align: start; font: inherit; cursor: pointer; }
.source-switch-card:hover { border-color: var(--reader-accent); background: color-mix(in srgb, var(--reader-accent) 4%, var(--reader-paper)); }
.source-switch-card:focus-visible { outline: var(--focus-ring); outline-offset: 2px; }
.source-switch-card:disabled { opacity: .55; cursor: default; }
.source-switch-card-heading { display: flex; align-items: center; justify-content: space-between; gap: 1rem; width: 100%; font-size: .95rem; }
.source-switch-card-heading .icon { flex: none; color: var(--reader-muted); }
.source-switch-book { font-size: .82rem; line-height: 1.5; }
.source-switch-book > span { color: var(--reader-muted); }
.source-switch-chapter { display: flex; align-items: baseline; gap: .5rem; font-size: .78rem; line-height: 1.6; color: var(--reader-muted); }
.source-switch-chapter > span { flex: none; font-size: .7rem; }
.source-switch .catalog-feedback { margin-top: 1rem; }

/* Reading tools share the reader modal, including narrow phone layouts. */
.reading-tools { display: grid; gap: 1rem; padding: 1rem; overflow-wrap: anywhere; }
.reading-tool-tabs { display: flex; flex-wrap: wrap; gap: .5rem; }
.reading-tool-tabs [aria-pressed="true"] { font-weight: bold; outline: 2px solid currentColor; }
.reading-tools section { display: grid; gap: .75rem; }
.reading-tools label { display: grid; gap: .3rem; }
.reading-tools input, .reading-tools textarea, .reading-tools select { max-width: 100%; min-width: 0; }
.reading-tools blockquote { margin: 0; max-height: 8rem; overflow: auto; }
.reading-tool-results { max-height: 45vh; overflow: auto; margin: 0; padding-left: 1.5rem; }
.reading-tool-results li { margin-block: .6rem; }
.reading-tool-results span { display: block; white-space: pre-wrap; }
.reading-tool-range { display: flex; gap: 1rem; }
.reading-tool-range label { min-width: 0; }
.toc-list li:has(.toc-collapse) { display: flex; }
.toc-list .toc-collapse { width: 2rem; flex: 0 0 2rem; justify-content: center; }

.reading-tools { min-height: 0; }
.reading-tools button, .reading-tools input, .reading-tools textarea, .reading-tools select { font: inherit; }
.reading-tool-tabs .button { flex: 1 1 auto; min-height: 2.5rem; font-size: .875rem; }
.reading-tool-tabs .button[aria-pressed="true"] { color: var(--reader-accent); background: var(--reader-surface); outline: none; border-color: var(--reader-accent); }
.reading-tools input, .reading-tools textarea, .reading-tools select { width: 100%; box-sizing: border-box; border: 1px solid var(--reader-line); border-radius: .5rem; padding: .6rem; background: var(--reader-paper); color: var(--reader-ink); }
.reading-tools textarea { min-height: 5rem; resize: vertical; }
.reading-tools form { display: grid; gap: .6rem; }
.reading-tools p { margin: .3rem 0; font-size: .9rem; line-height: 1.6; }
.reading-tool-results .button { text-align: start; width: 100%; margin-top: .25rem; }
.reading-tools blockquote { border-inline-start: 3px solid var(--reader-accent); padding: .5rem .75rem; line-height: 1.6; }
.source-capabilities { margin-block: 12px; overflow-wrap: anywhere; }
.source-capabilities summary { cursor: pointer; }
.source-capabilities dl { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 8px; }
.source-capabilities dl > div { padding: 8px; border: 1px solid currentColor; border-radius: 6px; }
.source-capabilities dd { margin: 4px 0 0; }