:root {
  color-scheme: light;
}

@font-face {
  font-family: "Source Han Serif SC";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src:
    local("Source Han Serif SC"),
    local("Source Han Serif CN"),
    url("https://raw.githubusercontent.com/adobe-fonts/source-han-serif/release/OTF/SimplifiedChinese/SourceHanSerifSC-Regular.otf")
      format("opentype");
}

:root {
  --bg: #f7f5ef;
  --bg-soft: #efeee7;
  --surface: #fffdf8;
  --surface-strong: #f1f6f2;
  --text: #26231f;
  --muted: #706a60;
  --border: #ded7ca;
  --accent: #7f2f2c;
  --accent-strong: #244f40;
  --accent-soft: #e7d7d0;
  --shadow: 0 18px 48px rgba(49, 42, 31, 0.1);
  --reader-size: 18px;
  --reader-line: 1.92;
  --header-height: 74px;
  --content-width: 760px;
}

[data-theme="dark"] {
  color-scheme: dark;
  --bg: #161716;
  --bg-soft: #1f211f;
  --surface: #20231f;
  --surface-strong: #18241f;
  --text: #eee9dc;
  --muted: #bbb2a3;
  --border: #39382f;
  --accent: #d58a7a;
  --accent-strong: #9ed0b8;
  --accent-soft: #3a2824;
  --shadow: 0 18px 48px rgba(0, 0, 0, 0.28);
}

[data-font-size="small"] {
  --reader-size: 16px;
  --reader-line: 1.88;
}

[data-font-size="large"] {
  --reader-size: 21px;
  --reader-line: 1.98;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 22px);
}

body {
  margin: 0;
  background:
    linear-gradient(90deg, rgba(36, 79, 64, 0.055), transparent 30%, transparent 70%, rgba(127, 47, 44, 0.045)),
    var(--bg);
  color: var(--text);
  font-family:
    "Source Han Serif SC",
    ui-serif,
    "Noto Serif SC",
    "Songti SC",
    SimSun,
    Georgia,
    serif;
  min-width: 320px;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  font: inherit;
}

body.reader-toc-open {
  overflow: hidden;
}

.progress {
  position: fixed;
  inset: 0 0 auto;
  height: 3px;
  z-index: 50;
  background: transparent;
}

.progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--accent-strong), var(--accent));
  transition: width 120ms ease;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  min-height: var(--header-height);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 24px;
  padding: 14px clamp(18px, 4vw, 54px);
  border-bottom: 1px solid color-mix(in srgb, var(--border) 80%, transparent);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(16px);
  transform: translateY(0);
  transition:
    transform 180ms ease,
    border-color 180ms ease,
    background 180ms ease;
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
}

.site-header.is-hidden {
  transform: translateY(calc(-100% - 4px));
}

.site-header:focus-within {
  transform: translateY(0);
}

.chapter-fab,
.sidebar-close {
  display: none;
}

.toc-backdrop {
  display: none;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  letter-spacing: 0;
}

.brand-mark {
  display: inline-grid;
  width: 34px;
  aspect-ratio: 1;
  place-items: center;
  border: 1px solid var(--accent);
  color: var(--accent);
  font-family: Georgia, serif;
  font-size: 19px;
}

.top-nav {
  display: flex;
  justify-content: center;
  gap: 22px;
  color: var(--muted);
  font-size: 14px;
}

.top-nav a,
.chapter-fab,
.secondary-link,
.toc-list a {
  transition:
    color 140ms ease,
    border-color 140ms ease,
    background 140ms ease,
    box-shadow 140ms ease,
    transform 140ms ease;
}

.top-nav a:hover,
.toc-list a:hover {
  color: var(--accent);
}

.reader-controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

.segmented {
  display: inline-grid;
  grid-template-columns: repeat(3, 38px);
  border: 1px solid var(--border);
  background: var(--surface);
}

.segmented button,
.theme-toggle,
.toc-toggle {
  min-height: 36px;
  border: 0;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  font-size: 13px;
}

.segmented button + button {
  border-left: 1px solid var(--border);
}

.segmented button[aria-pressed="true"] {
  background: var(--accent-strong);
  color: #fffdf8;
}

.theme-toggle,
.toc-toggle {
  padding: 0 14px;
  border: 1px solid var(--border);
  background: var(--surface);
}

.toc-toggle {
  display: none;
}

.toc-toggle::after {
  content: "";
  width: 7px;
  height: 7px;
  margin-left: 8px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: translateY(-2px) rotate(45deg);
  transition: transform 140ms ease;
}

.toc-toggle[aria-expanded="true"]::after {
  transform: translateY(2px) rotate(225deg);
}

.theme-toggle:hover,
.toc-toggle:hover,
.secondary-link:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.hero {
  padding: clamp(76px, 12vh, 132px) clamp(20px, 5vw, 64px) clamp(48px, 7vh, 84px);
  border-bottom: 1px solid var(--border);
}

.hero-inner {
  max-width: 1080px;
  margin: 0 auto;
}

.meta-line {
  max-width: var(--content-width);
  margin: 0 0 24px;
  color: var(--accent-strong);
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  font-size: 14px;
}

.hero h1 {
  margin: 0;
  font-size: clamp(58px, 13vw, 150px);
  line-height: 0.88;
  font-weight: 600;
  letter-spacing: 0;
}

.title-original,
.title-translation {
  display: inline-block;
}

.title-translation {
  margin-left: 0.08em;
  font-size: 0.42em;
  vertical-align: 0.16em;
}

.author {
  margin: 22px 0 0;
  color: var(--muted);
  font-size: clamp(20px, 3vw, 34px);
}

.intro {
  max-width: 760px;
  margin: 34px 0 0;
  color: var(--text);
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.85;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 34px;
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
}

.primary-link,
.secondary-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 22px;
  border: 1px solid var(--accent);
}

.primary-link {
  background: var(--accent);
  color: #fffdf8;
}

.secondary-link {
  border-color: var(--border);
  color: var(--muted);
  background: color-mix(in srgb, var(--surface) 70%, transparent);
}

.overview,
.reader-shell {
  padding: clamp(34px, 5vw, 64px) clamp(18px, 5vw, 64px);
}

.overview-inner,
.reader-shell {
  width: min(1180px, 100%);
  margin: 0 auto;
}

.overview-inner {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(260px, 0.9fr);
  gap: 34px 48px;
}

.overview-block {
  border-top: 1px solid var(--border);
  padding-top: 20px;
}

.overview-block h2,
.section-heading,
.sidebar-title {
  margin: 0 0 16px;
  color: var(--text);
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  font-size: 15px;
  font-weight: 700;
}

.overview-block p {
  margin: 0;
  color: var(--muted);
  line-height: 1.8;
}

.section-heading,
.sidebar-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.reserve-grid {
  grid-column: 1 / -1;
}

.reserve-items {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.reserve-items a {
  min-height: 58px;
  display: flex;
  align-items: center;
  border-top: 1px solid var(--border);
  color: var(--accent-strong);
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
}

.reader-shell {
  display: grid;
  grid-template-columns: minmax(230px, 290px) minmax(0, var(--content-width));
  justify-content: center;
  align-items: start;
  gap: clamp(28px, 5vw, 68px);
}

.reader-sidebar {
  position: sticky;
  top: calc(var(--header-height) + 26px);
  max-height: calc(100vh - var(--header-height) - 48px);
  overflow: auto;
  border-top: 1px solid var(--border);
  padding-top: 18px;
  scrollbar-width: thin;
}

.sidebar-actions {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.chapter-count {
  min-width: 34px;
  padding: 2px 8px;
  text-align: center;
  border: 1px solid var(--border);
  color: var(--muted);
  font-weight: 500;
}

.toc-list {
  display: grid;
  gap: 4px;
}

.toc-list a {
  display: block;
  padding: 8px 10px;
  border-left: 2px solid transparent;
  color: var(--muted);
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  font-size: 14px;
  line-height: 1.45;
}

.toc-list a.is-active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: color-mix(in srgb, var(--accent-soft) 42%, transparent);
}

.toc-list a.depth-3 {
  padding-left: 24px;
  font-size: 13px;
}

.home-toc {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px 12px;
}

.book-content {
  width: min(100%, var(--content-width));
  padding-bottom: 70px;
}

.book-content h1,
.book-content h2,
.book-content h3 {
  color: var(--text);
  font-weight: 650;
  letter-spacing: 0;
}

.book-content h1 {
  margin: 0 0 34px;
  font-size: clamp(42px, 8vw, 82px);
  line-height: 1;
}

.book-content h2 {
  margin: 72px 0 22px;
  padding-top: 12px;
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1.25;
}

.book-content h3 {
  margin: 42px 0 16px;
  font-size: 24px;
  line-height: 1.3;
}

.book-content p,
.book-content blockquote {
  font-size: var(--reader-size);
  line-height: var(--reader-line);
}

.book-content p {
  margin: 0 0 1.15em;
  text-align: justify;
}

.book-content blockquote {
  margin: 0 0 1.25em;
  padding: 0 0 0 18px;
  border-left: 3px solid var(--accent-soft);
  color: var(--muted);
}

.book-content blockquote p {
  margin: 0;
  text-align: start;
}

.book-content hr {
  width: 84px;
  margin: 48px 0;
  border: 0;
  border-top: 1px solid var(--border);
}

.loading,
.muted {
  color: var(--muted);
}

.site-footer {
  padding: 34px clamp(18px, 5vw, 64px) 54px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  font-size: 14px;
}

.site-footer p {
  width: min(1180px, 100%);
  margin: 0 auto;
}

.site-footer a {
  color: var(--accent);
}

@media (max-width: 900px) {
  .site-header {
    grid-template-columns: 1fr auto;
  }

  .top-nav {
    display: none;
  }

  .overview-inner,
  .reader-shell {
    grid-template-columns: 1fr;
  }

  .chapter-fab {
    position: fixed;
    right: 18px;
    bottom: max(18px, env(safe-area-inset-bottom));
    z-index: 52;
    display: grid;
    width: 54px;
    height: 54px;
    place-items: center;
    padding: 0;
    border: 1px solid color-mix(in srgb, var(--accent-strong) 26%, var(--border));
    border-radius: 50%;
    background:
      radial-gradient(circle at 35% 28%, color-mix(in srgb, var(--surface) 92%, white), transparent 48%),
      color-mix(in srgb, var(--surface) 90%, var(--bg));
    color: var(--accent-strong);
    box-shadow:
      0 14px 30px rgba(38, 35, 31, 0.14),
      inset 0 1px 0 color-mix(in srgb, white 72%, transparent);
    backdrop-filter: blur(14px);
    cursor: pointer;
  }

  .chapter-fab-icon {
    width: 25px;
    height: 25px;
    fill: none;
    stroke: currentColor;
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-width: 1.55;
  }

  .chapter-fab:hover,
  .chapter-fab:focus-visible {
    transform: translateY(-2px);
    border-color: var(--accent);
    color: var(--accent);
    box-shadow:
      0 18px 36px rgba(38, 35, 31, 0.18),
      inset 0 1px 0 color-mix(in srgb, white 80%, transparent);
    outline: none;
  }

  .toc-backdrop {
    position: fixed;
    inset: 0;
    z-index: 55;
    display: block;
    background: rgba(18, 17, 15, 0.42);
    opacity: 0;
    pointer-events: none;
    transition: opacity 160ms ease;
  }

  .toc-backdrop.is-visible {
    opacity: 1;
    pointer-events: auto;
  }

  .reader-sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 60;
    width: min(86vw, 350px);
    max-height: none;
    padding: 24px 18px 34px;
    border-top: 0;
    border-right: 1px solid var(--border);
    background: var(--surface);
    box-shadow: var(--shadow);
    transform: translateX(-100%);
    transition: transform 180ms ease;
  }

  .reader-sidebar.is-open {
    transform: translateX(0);
  }

  .sidebar-close {
    display: inline-flex;
    align-items: center;
    min-height: 30px;
    padding: 0 10px;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--muted);
    cursor: pointer;
    font-family:
      ui-sans-serif,
      system-ui,
      -apple-system,
      BlinkMacSystemFont,
      "Segoe UI",
      sans-serif;
    font-size: 13px;
  }

  .toc-list.home-toc {
    display: none;
  }

  .toc-toggle {
    display: inline-flex;
    align-items: center;
    border-radius: 999px;
    background: color-mix(in srgb, var(--surface) 82%, transparent);
  }

  .toc-list.home-toc.is-open {
    display: grid;
    grid-template-columns: 1fr;
  }

  .reserve-items {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 620px) {
  :root {
    --header-height: 104px;
  }

  .site-header {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .reader-controls {
    width: 100%;
    justify-content: space-between;
  }

  .segmented {
    grid-template-columns: repeat(3, minmax(42px, 1fr));
    flex: 1;
  }

  .theme-toggle {
    min-width: 74px;
  }

  .hero {
    padding-top: 54px;
  }

  .hero h1 {
    font-size: clamp(54px, 22vw, 86px);
  }

  .home-toc.is-open {
    max-height: 420px;
    overflow: auto;
  }

  .reserve-items {
    grid-template-columns: 1fr;
  }

  .book-content p {
    text-align: start;
  }
}