/* Software Engineering Metrics — site stylesheet
 *
 * Built on the Lily Design System class-hook conventions
 * (see https://lilydesignsystem.com/) plus book-specific additions for
 * the sidebar, breadcrumbs, and chapter pager.
 *
 * assets/themes/{light,dark}.css are the two real theme stylesheets from
 * the pinned @lilydesignsystem/themes package (synced verbatim by
 * `pnpm run themes`; never hand-edited — see scripts/sync-themes.mjs),
 * loaded by @lilydesignsystem/svelte-theme-picker (wired up in
 * src/routes/[locale]/+layout.svelte). Each theme file, scoped to
 * :root[data-theme="…"], defines Lily's raw palette (`--color-primary`,
 * `--color-base-100`, ...) plus Lily's own derived bridge tokens
 * (`--lily-surface`, `--lily-text`, `--lily-border`, `--lily-shadow-sm/lg`,
 * `--lily-radius-md/lg`, `--lily-font-body`, `--lily-font-mono`, ...) and
 * the full 492-component Lily class-hook stylesheet (zero-specificity
 * `:where(...)`/`@layer`, so every rule below still wins the cascade for
 * any hook this site also targets, e.g. `.card`, `.hero`).
 *
 * A handful of tokens Lily's palette doesn't define by name (a hover shade
 * for the primary colour, a third "subtle" text tier, a light background
 * tint of the primary colour) are computed here, from the same per-theme
 * `--color-*` primitives, so they still switch automatically with the
 * active theme. Every other rule below reads a token via var(...); it
 * never sets one Lily already provides, so it works under either theme
 * unmodified.
 */

:root {
  --lily-primary-hover: color-mix(in oklch, var(--color-primary) 85%, black);
  --lily-text-subtle: color-mix(in oklch, var(--color-base-content) 50%, transparent);
  /* Mixing toward --color-base-100 (not black/transparent, unlike the two
     tokens above) needs oklab, not oklch: Lily's light theme writes it as
     oklch(100% 0 0) — chroma 0, but an explicit numeric hue of 0 rather
     than the CSS "none" keyword, so oklch's circular hue interpolation
     pulls the mix toward hue 0 (pink) instead of carrying the chromatic
     colour's own hue through, as a truly achromatic value would. oklab's
     Cartesian a/b axes have no hue channel to misinterpret. */
  --lily-tint: color-mix(in oklab, var(--color-primary) 12%, var(--color-base-100));
  --lily-content-max: 78rem;
  --lily-prose-max: 42rem;
  --lily-sidebar-width: 18rem;
}

/* @lilydesignsystem/svelte-text-size-picker's seven-step scale
 * (DEFAULT_SIZES), applied as a root font-size multiplier so every rem-based
 * size in this file scales with it. */
:root[data-text-size="smallest"] { font-size: 62.5%; }
:root[data-text-size="smaller"] { font-size: 75%; }
:root[data-text-size="small"] { font-size: 87.5%; }
:root[data-text-size="normal"] { font-size: 100%; }
:root[data-text-size="large"] { font-size: 112.5%; }
:root[data-text-size="larger"] { font-size: 125%; }
:root[data-text-size="largest"] { font-size: 137.5%; }

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--lily-font-body);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--lily-text);
  background: var(--lily-surface);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 0.15em;
}
a:hover { color: var(--lily-primary-hover); }
a:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: 2px;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin: 2rem 0 1rem;
}
h1 { font-size: 2.5rem; }
h2 { font-size: 1.875rem; }
h3 { font-size: 1.375rem; }
h4 { font-size: 1.125rem; }

p { margin: 0 0 1rem; }

code, pre {
  font-family: var(--lily-font-mono);
  font-size: 0.9em;
}
code {
  /* --color-neutral is Lily's own token for exactly this: "footer bars,
     code blocks, tooltips" (see its doc comment in the theme file). */
  background: color-mix(in oklab, var(--color-neutral) 12%, var(--color-base-100));
  color: var(--color-neutral);
  padding: 0.1em 0.35em;
  border-radius: 4px;
}
pre {
  background: var(--color-neutral);
  color: var(--color-neutral-content);
  padding: 1rem;
  border-radius: var(--lily-radius-md);
  overflow-x: auto;
  line-height: 1.5;
}
pre code {
  background: transparent;
  color: inherit;
  padding: 0;
}

blockquote {
  margin: 1.5rem 0;
  padding: 0.5rem 1.25rem;
  border-left: 4px solid var(--lily-border-strong);
  color: var(--lily-text-muted);
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.95rem;
}
th, td {
  text-align: left;
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--lily-border);
}
th { font-weight: 700; color: var(--lily-text); }

kbd {
  font-family: var(--lily-font-mono);
  font-size: 0.85em;
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border-strong);
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 0.1em 0.4em;
}

/* Header & navigation */

.site-header {
  background: var(--lily-surface-alt);
  border-bottom: 1px solid var(--lily-border);
  position: sticky;
  top: 0;
  z-index: 50;
  box-shadow: var(--lily-shadow-sm);
}

.site-header-inner {
  max-width: var(--lily-content-max);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.site-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--lily-text);
  text-decoration: none;
}
.site-brand:hover { color: var(--color-primary); }
.site-brand-mark { width: 1.75rem; height: 1.75rem; display: inline-block; vertical-align: middle; }

.site-nav {
  display: flex;
  gap: 0.25rem;
  flex-wrap: wrap;
}
.site-nav a {
  color: var(--lily-text-muted);
  text-decoration: none;
  padding: 0.5rem 0.75rem;
  border-radius: var(--lily-radius-md);
  font-size: 0.95rem;
  transition: background 150ms;
}
.site-nav a:hover { background: var(--lily-border); color: var(--lily-text); }
.site-nav a[aria-current="page"] {
  color: var(--color-primary);
  font-weight: 600;
  background: var(--lily-tint);
}

/* @lilydesignsystem/svelte-picker-bar: theme, locale, text-size, and share
 * pickers, wired up in +layout.svelte's header. Each ships zero CSS; the
 * class hooks and the positioning requirement below are each package's own
 * "Styling" doc. All four share one icon-button-opens-a-listbox shape, so
 * one rule set covers them. */

.picker-bar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.theme-picker, .locale-picker, .text-size-picker, .share-picker, .search-picker, .link-picker {
  position: relative;
  display: inline-block;
}

.theme-picker-button, .locale-picker-button, .text-size-picker-button, .share-picker-button, .search-picker-button, .link-picker-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  inline-size: 2.25rem;
  block-size: 2.25rem;
  color: var(--lily-text-muted);
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border-strong);
  border-radius: var(--lily-radius-md);
  cursor: pointer;
}
.theme-picker-button:hover, .locale-picker-button:hover, .text-size-picker-button:hover, .share-picker-button:hover, .search-picker-button:hover, .link-picker-button:hover {
  color: var(--lily-text);
  border-color: var(--color-primary);
}
.theme-picker-button:focus-visible, .locale-picker-button:focus-visible, .text-size-picker-button:focus-visible, .share-picker-button:focus-visible, .search-picker-button:focus-visible, .link-picker-button:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 1px;
}
.theme-picker-button[aria-expanded="true"], .locale-picker-button[aria-expanded="true"], .text-size-picker-button[aria-expanded="true"], .share-picker-button[aria-expanded="true"], .search-picker-button[aria-expanded="true"], .link-picker-button[aria-expanded="true"] {
  color: var(--color-primary);
  border-color: var(--color-primary);
}
.theme-picker-icon, .locale-picker-icon, .text-size-picker-icon, .share-picker-icon, .search-picker-icon, .link-picker-icon {
  font-size: 1.1rem;
  line-height: 1;
}

.theme-picker-list, .locale-picker-list, .text-size-picker-list, .share-picker-list, .link-picker-list {
  position: absolute;
  z-index: 20;
  inset-block-start: calc(100% + 0.35rem);
  inset-inline-start: 0;
  margin: 0;
  padding: 0.35rem;
  list-style: none;
  min-inline-size: 10rem;
  max-block-size: 20rem;
  overflow-y: auto;
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border);
  border-radius: var(--lily-radius-md);
  box-shadow: var(--lily-shadow-lg);
}
.theme-picker-list[hidden], .locale-picker-list[hidden], .text-size-picker-list[hidden], .share-picker-list[hidden], .link-picker-list[hidden] {
  display: none;
}
.theme-picker-option, .locale-picker-option, .text-size-picker-option, .share-picker-list-item {
  padding: 0.4rem 0.6rem;
  border-radius: var(--lily-radius-md);
  cursor: pointer;
  text-align: start;
  white-space: nowrap;
}
.theme-picker-option[data-active], .locale-picker-option[data-active], .text-size-picker-option[data-active] {
  background: var(--lily-border);
}
.theme-picker-option[aria-selected="true"], .locale-picker-option[aria-selected="true"], .text-size-picker-option[aria-selected="true"] {
  color: var(--color-primary);
  font-weight: 600;
}
/* The search picker's panel holds an input and a submit button in a row. */
.search-picker-panel {
  position: absolute;
  z-index: 20;
  inset-block-start: calc(100% + 0.35rem);
  inset-inline-start: 0;
  padding: 0.35rem;
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border);
  border-radius: var(--lily-radius-md);
  box-shadow: var(--lily-shadow-lg);
}
.search-picker-panel[hidden] { display: none; }
.search-picker-form { display: flex; gap: 0.35rem; align-items: center; }
.search-picker-input {
  min-inline-size: 14rem;
  block-size: 2.25rem;
  padding: 0 0.6rem;
  font: inherit;
  color: var(--lily-text);
  background: var(--lily-surface);
  border: 1px solid var(--lily-border-strong);
  border-radius: var(--lily-radius-md);
}
.search-picker-submit {
  inline-size: 2.25rem;
  block-size: 2.25rem;
  color: var(--lily-text-muted);
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border-strong);
  border-radius: var(--lily-radius-md);
  cursor: pointer;
}

/* Narrow screens: the search field opens over the row of picker buttons,
 * full width inside the header, so it covers neither the nav links nor the
 * content. The other pickers are hidden only while searching. The theme
 * positions the panel inside :where() (no specificity), so these plain class
 * selectors override it. */
@media (max-width: 40rem) {
  .picker-bar { position: relative; }
  .search-picker { position: static; }
  .search-picker-panel {
    inset-block: 0;
    inset-inline: 0;
    display: flex;
    align-items: center;
    padding: 0;
    background: var(--lily-surface-alt);
    border: 0;
    border-radius: 0;
    box-shadow: none;
  }
  .search-picker-panel[hidden] { display: none; }
  .search-picker-form { inline-size: 100%; }
  .search-picker-input { flex: 1; min-inline-size: 0; }
  .picker-bar:has(.search-picker-button[aria-expanded="true"]) > :not(.search-picker) { visibility: hidden; }
  .search-picker-button[aria-expanded="true"] { visibility: hidden; }
}
.link-picker-tooltip, .search-picker-tooltip, .theme-picker-tooltip, .locale-picker-tooltip, .text-size-picker-tooltip, .share-picker-tooltip {
  position: absolute;
  z-index: 20;
  inset-block-start: calc(100% + 0.35rem);
  inset-inline-end: 0;
  padding: 0.2rem 0.5rem;
  font-size: 0.8rem;
  inline-size: max-content;
  white-space: nowrap;
  color: var(--lily-text);
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border);
  border-radius: var(--lily-radius-md);
}
.link-picker-tooltip[hidden], .search-picker-tooltip[hidden], .theme-picker-tooltip[hidden], .locale-picker-tooltip[hidden], .text-size-picker-tooltip[hidden], .share-picker-tooltip[hidden] { display: none; }

.share-picker-target, .share-picker-copy {
  display: block;
  padding: 0.4rem 0.6rem;
  border-radius: var(--lily-radius-md);
  color: inherit;
  text-decoration: none;
  background: none;
  border: none;
  font: inherit;
  text-align: start;
  cursor: pointer;
  inline-size: 100%;
}
.share-picker-target:hover, .share-picker-copy:hover { background: var(--lily-border); }

/* The copy-link aria-live announcement. Screen-reader-only: the user
 * agent's default <p> margin was otherwise adding invisible height below
 * the share button, which flexbox's align-items: center on .picker-bar
 * then centered along with the rest of .share-picker's box, pushing the
 * button (and its dropdown, positioned relative to the same box) visibly
 * higher than the other three pickers in the row. position: absolute
 * removes it from flow entirely rather than merely zeroing its margin, so
 * a future, longer status string can never reintroduce the same shift. */
.share-picker-status {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Main content */

.site-main {
  max-width: var(--lily-content-max);
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

.site-main.has-sidebar {
  display: grid;
  grid-template-columns: var(--lily-sidebar-width) minmax(0, 1fr);
  gap: 3rem;
  align-items: start;
}

.prose { max-width: var(--lily-prose-max); }
.prose ul, .prose ol { padding-left: 1.5rem; }
.prose li { margin-bottom: 0.25rem; }
.prose img { max-width: 100%; height: auto; border-radius: var(--lily-radius-md); }

/* Hero */

.hero {
  text-align: center;
  padding: 2.5rem 1rem 1rem;
  max-width: 48rem;
  margin: 0 auto;
}
.hero-eyebrow {
  display: inline-block;
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-primary);
  background: var(--lily-tint);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  margin-bottom: 1rem;
}
.hero h1 {
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  margin: 0.5rem 0 1rem;
  color: var(--color-primary-content);
}
.hero-tagline {
  font-size: 1.25rem;
  color: var(--lily-text-muted);
  margin: 0 auto 2rem;
  max-width: 40rem;
}

/* Buttons */

.button {
  display: inline-block;
  font: inherit;
  font-weight: 600;
  text-decoration: none;
  padding: 0.75rem 1.5rem;
  border-radius: var(--lily-radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all 150ms;
  line-height: 1.2;
}
.button-primary {
  background: var(--color-primary);
  color: var(--color-primary-content);
  border-color: var(--color-primary);
}
.button-primary:hover {
  background: var(--lily-primary-hover);
  border-color: var(--lily-primary-hover);
  color: var(--color-primary-content);
}
.button-secondary {
  background: var(--lily-surface-alt);
  color: var(--color-primary);
  border-color: var(--color-primary);
}
.button-secondary:hover {
  background: var(--lily-tint);
}

.button-row {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
  margin: 1.5rem 0;
}

/* Card grids */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.card {
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border);
  border-radius: var(--lily-radius-lg);
  padding: 1.5rem;
  box-shadow: var(--lily-shadow-sm);
  transition: transform 150ms, box-shadow 150ms;
}
.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--lily-shadow-lg);
}
.card-heading {
  margin: 0 0 0.5rem;
  font-size: 1.25rem;
}
.card-description {
  margin: 0 0 1rem;
  color: var(--lily-text-muted);
}
.card-meta {
  font-size: 0.875rem;
  color: var(--lily-text-subtle);
  margin: 0;
}

a.card { color: inherit; text-decoration: none; }
a.card:hover { color: inherit; }

/* Home page contents: nested list of parts and chapters */

.home-contents > li { margin-top: 1rem; font-weight: 700; }
.home-contents ul { font-weight: 400; margin-top: 0.35rem; }
.home-contents a { text-decoration: none; }

/* Sections */

.section {
  margin: 4rem 0;
}
.section-heading {
  text-align: center;
  margin-bottom: 2rem;
}
.section-heading-eyebrow {
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-primary);
  margin: 0 0 0.5rem;
}
.section-heading h2 {
  margin: 0;
}

/* Footer */

.site-footer {
  background: var(--lily-surface-alt);
  border-top: 1px solid var(--lily-border);
  margin-top: 4rem;
  padding: 2rem 1.5rem;
}
.site-footer-inner {
  max-width: var(--lily-content-max);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  justify-content: space-between;
  align-items: center;
  font-size: 0.95rem;
  color: var(--lily-text-muted);
}
.site-footer p { margin: 0; }
.site-footer-links { display: flex; gap: 1rem; flex-wrap: wrap; }

/* Tag list (chips for categories) */

.tag-list {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  list-style: none;
  padding: 0;
  margin: 0 0 1.5rem;
}
.tag {
  display: inline-block;
  font-size: 0.8125rem;
  background: var(--lily-tint);
  color: var(--color-primary);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-weight: 600;
}

/* Detail/summary FAQ */

details.faq-item {
  background: var(--lily-surface-alt);
  border: 1px solid var(--lily-border);
  border-radius: var(--lily-radius-md);
  padding: 1rem 1.25rem;
  margin-bottom: 0.75rem;
}
details.faq-item[open] { border-color: var(--color-primary); }
details.faq-item summary { cursor: pointer; font-weight: 600; list-style: none; }
details.faq-item summary::-webkit-details-marker { display: none; }
details.faq-item summary::after {
  content: "+";
  float: right;
  font-size: 1.25rem;
  color: var(--color-primary);
  font-weight: 400;
}
details.faq-item[open] summary::after { content: "−"; }
details.faq-item p { margin-top: 0.75rem; }

/* Skip link */

.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  background: var(--color-primary);
  color: var(--color-primary-content);
  padding: 0.5rem 1rem;
  border-radius: 4px;
  text-decoration: none;
  z-index: 100;
  transition: top 150ms;
}
.skip-link:focus { top: 1rem; color: var(--color-primary-content); }

/* Banner */

.callout {
  background: var(--lily-tint);
  border-left: 4px solid var(--color-primary);
  padding: 1rem 1.25rem;
  border-radius: 0 var(--lily-radius-md) var(--lily-radius-md) 0;
  margin: 1.5rem 0;
}
.callout-warning { background: color-mix(in oklab, var(--color-warning) 12%, var(--color-base-100)); border-left-color: var(--color-warning); }
.callout-success { background: color-mix(in oklab, var(--color-success) 12%, var(--color-base-100)); border-left-color: var(--color-success); }

/* ---------------------------------------------------------------------- */
/* Book-specific: sidebar navigation                                      */
/* ---------------------------------------------------------------------- */

.sidebar {
  position: sticky;
  top: 5.5rem;
  max-height: calc(100vh - 7rem);
  overflow-y: auto;
  font-size: 0.9rem;
  padding-right: 0.5rem;
}
.sidebar-search {
  display: block;
  width: 100%;
  font: inherit;
  font-size: 0.9rem;
  padding: 0.5rem 0.75rem;
  border: 2px solid var(--lily-border-strong);
  border-radius: var(--lily-radius-md);
  margin-bottom: 1rem;
  background: var(--lily-surface-alt);
}
.sidebar-search:focus { outline: none; border-color: var(--color-primary); }

.sidebar-part {
  border: none;
  margin-bottom: 0.25rem;
}
.sidebar-part summary {
  cursor: pointer;
  list-style: none;
  font-weight: 700;
  padding: 0.4rem 0.5rem;
  border-radius: var(--lily-radius-md);
  color: var(--lily-text);
}
.sidebar-part summary::-webkit-details-marker { display: none; }
.sidebar-part summary:hover { background: var(--lily-border); }
.sidebar-part summary .part-number {
  display: inline-block;
  min-width: 1.5rem;
  color: var(--color-primary);
}

.sidebar-chapter-list {
  list-style: none;
  margin: 0.15rem 0 0.75rem;
  padding: 0 0 0 0.5rem;
  border-left: 2px solid var(--lily-border);
}
.sidebar-chapter-list li { margin: 0; }
.sidebar-chapter-list a {
  display: block;
  padding: 0.3rem 0.6rem;
  border-radius: var(--lily-radius-md);
  color: var(--lily-text-muted);
  text-decoration: none;
  line-height: 1.35;
}
.sidebar-chapter-list a:hover { background: var(--lily-border); color: var(--lily-text); }
.sidebar-chapter-list a[aria-current="page"] {
  background: var(--lily-tint);
  color: var(--color-primary);
  font-weight: 600;
}
.sidebar-chapter-list .decimal { color: var(--lily-text-subtle); margin-right: 0.35em; font-variant-numeric: tabular-nums; }
.sidebar-part[data-current="true"] summary { color: var(--color-primary); }

/* Book-specific: breadcrumb, chapter meta, pager */

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  font-size: 0.875rem;
  color: var(--lily-text-subtle);
  margin-bottom: 1rem;
}
.breadcrumb a { color: var(--lily-text-subtle); text-decoration: none; }
.breadcrumb a:hover { color: var(--color-primary); text-decoration: underline; }
.breadcrumb .sep { color: var(--lily-border-strong); }

.chapter-decimal {
  display: inline-block;
  font-family: var(--lily-font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--color-primary);
  background: var(--lily-tint);
  padding: 0.15rem 0.6rem;
  border-radius: 9999px;
  margin-bottom: 0.75rem;
}

.chapter-pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin: 3rem 0 1rem;
  padding-top: 2rem;
  border-top: 1px solid var(--lily-border);
}
.chapter-pager-link {
  display: block;
  padding: 1rem 1.25rem;
  border: 1px solid var(--lily-border);
  border-radius: var(--lily-radius-lg);
  text-decoration: none;
  color: var(--lily-text);
  transition: border-color 150ms, box-shadow 150ms;
}
.chapter-pager-link:hover { border-color: var(--color-primary); box-shadow: var(--lily-shadow-sm); }
.chapter-pager-link.next { text-align: right; }
.chapter-pager-label {
  display: block;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--lily-text-subtle);
  margin-bottom: 0.25rem;
}
.chapter-pager-title { font-weight: 600; }

.toc-search {
  display: block;
  width: 100%;
  max-width: 28rem;
  font: inherit;
  padding: 0.75rem 1rem;
  border: 2px solid var(--lily-border-strong);
  border-radius: var(--lily-radius-md);
  margin: 0 0 2rem;
  background: var(--lily-surface-alt);
}
.toc-search:focus { outline: none; border-color: var(--color-primary); }

.toc-part { margin-bottom: 2.5rem; }
.toc-part-heading {
  border-bottom: 2px solid var(--lily-border);
  padding-bottom: 0.5rem;
}
.toc-part-heading .part-number {
  margin-right: 0.6rem;
  color: var(--color-primary);
  font-weight: 700;
}
.toc-chapter-list { list-style: none; margin: 1rem 0 0; padding: 0; }
.toc-chapter-list li { margin-bottom: 0.35rem; }
.toc-chapter-list a { text-decoration: none; }
.toc-chapter-list .decimal {
  display: inline-block;
  min-width: 3rem;
  font-family: var(--lily-font-mono);
  color: var(--lily-text-subtle);
  font-variant-numeric: tabular-nums;
}
.toc-chapter-list[hidden] { display: none; }

/* Responsive helpers */

@media (max-width: 900px) {
  .site-main.has-sidebar {
    grid-template-columns: 1fr;
  }
  .sidebar {
    position: static;
    max-height: none;
    border-bottom: 1px solid var(--lily-border);
    padding-bottom: 1.5rem;
    margin-bottom: 1.5rem;
  }
}

@media (max-width: 640px) {
  .site-nav { width: 100%; justify-content: flex-start; }
  .site-main { padding: 2rem 1rem; }
  .hero { padding: 2rem 1rem 1rem; }
  .chapter-pager { grid-template-columns: 1fr; }
  .chapter-pager-link.next { text-align: left; }
}

/* Reduced motion */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Site search (spec/search/index.md) */
.site-search-results ol {
	padding-left: 1.25rem;
}
.site-search-results li {
	margin: 0 0 1.25rem;
}
.site-search-url {
	font-size: 0.8em;
	opacity: 0.7;
	word-break: break-all;
}
.site-search-results li p {
	margin: 0.25rem 0 0;
}

/* Link picker: a list of links, each filling its row. */
.link-picker-list { min-inline-size: 16rem; }
.link-picker-link {
  display: block;
  padding: 0.4rem 0.6rem;
  border-radius: var(--lily-radius-md);
  color: inherit;
  text-decoration: none;
  white-space: nowrap;
}
.link-picker-link:hover, .link-picker-link:focus-visible { background: var(--lily-border); }
.link-picker-link[aria-current="page"] { color: var(--color-primary); font-weight: 600; }