:root {
  color-scheme: light;
  --bg: #f4f6f8;
  --surface: #ffffff;
  --surface-2: #f9fbfc;
  --text: #1f2933;
  --muted: #637083;
  --line: #d8e0ea;
  --teal: #0f766e;
  --teal-dark: #0b5f59;
  --teal-soft: #e6fffb;
  --amber: #b45309;
  --amber-soft: #fff7ed;
  --blue: #1d4ed8;
  --shadow: 0 16px 42px rgba(15, 23, 42, 0.08);
  --radius: 8px;
  --header: 64px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Microsoft YaHei", "PingFang SC", "Segoe UI", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.68;
}

a { color: inherit; }

button, input {
  font: inherit;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -44px;
  z-index: 10;
  background: var(--teal);
  color: white;
  padding: 8px 12px;
  border-radius: 6px;
  transition: top 160ms ease;
}

.skip-link:focus { top: 10px; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  min-height: var(--header);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 12px clamp(16px, 4vw, 42px);
  background: rgba(255, 255, 255, 0.96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 800;
  min-width: max-content;
}

.brand-mark {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border-radius: 7px;
  background: var(--teal);
  color: white;
  font-weight: 900;
}

.top-nav {
  display: flex;
  gap: 6px;
  overflow-x: auto;
  padding-bottom: 2px;
}

.nav-link {
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  padding: 0 12px;
  border-radius: 7px;
  text-decoration: none;
  color: #334155;
  white-space: nowrap;
}

.nav-link:hover,
.nav-link.is-active {
  background: var(--teal-soft);
  color: var(--teal-dark);
}

main {
  width: min(1220px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0 72px;
}

.home-hero,
.subject-header,
.upload-guide,
.file-map,
.outline-content,
.outline-pane,
.pdf-viewer {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.home-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(260px, 0.75fr);
  gap: 28px;
  align-items: center;
  padding: clamp(22px, 5vw, 48px);
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--teal);
  font-size: 13px;
  font-weight: 800;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(28px, 5vw, 46px);
  line-height: 1.18;
  letter-spacing: 0;
}

h2 {
  margin: 0 0 12px;
  font-size: 22px;
  line-height: 1.35;
  letter-spacing: 0;
}

p { margin: 10px 0; }

.hero-copy p:last-child,
.subject-header p {
  max-width: 760px;
  color: var(--muted);
}

.site-preview {
  min-height: 240px;
  display: grid;
  align-content: center;
  gap: 12px;
  padding: 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background:
    linear-gradient(90deg, rgba(15, 118, 110, 0.08), rgba(180, 83, 9, 0.08)),
    var(--surface-2);
}

.preview-bar,
.preview-row,
.preview-note {
  border-radius: 6px;
  background: white;
  border: 1px solid var(--line);
}

.preview-bar { height: 46px; background: var(--teal); border-color: var(--teal); }
.preview-row { height: 18px; width: 86%; }
.preview-row.strong { height: 28px; width: 62%; }
.preview-row.short { width: 48%; }
.preview-note {
  width: max-content;
  padding: 6px 10px;
  color: var(--amber);
  background: var(--amber-soft);
}

.subject-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.subject-link {
  min-height: 128px;
  display: grid;
  grid-template-columns: 62px minmax(0, 1fr) 28px;
  align-items: center;
  gap: 16px;
  padding: 20px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  text-decoration: none;
  box-shadow: var(--shadow);
}

.subject-link:hover {
  border-color: #94d6ce;
  transform: translateY(-1px);
}

.subject-token {
  width: 58px;
  height: 58px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--teal-soft);
  color: var(--teal-dark);
  font-weight: 900;
}

.subject-copy {
  display: grid;
  gap: 4px;
  min-width: 0;
}

.subject-copy strong { font-size: 20px; color: var(--text); }
.subject-copy span { color: var(--muted); }
.subject-arrow { font-size: 28px; color: var(--teal); }

.upload-guide {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(260px, 1.1fr);
  gap: 22px;
  margin-top: 18px;
  padding: 24px;
}

.upload-guide ol {
  margin: 0;
  padding-left: 22px;
}

.file-maps {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.file-map { padding: 22px; box-shadow: none; }

code {
  background: #eef2f7;
  border: 1px solid #dde6f0;
  border-radius: 4px;
  padding: 1px 5px;
  font-family: Consolas, "Cascadia Mono", monospace;
  font-size: 0.92em;
}

.compact-list {
  margin: 10px 0 0;
  padding-left: 0;
  list-style: none;
}

.compact-list li {
  padding: 6px 0;
  border-bottom: 1px solid var(--line);
}

.subject-header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 24px;
  align-items: center;
  padding: clamp(20px, 4vw, 36px);
  margin-bottom: 16px;
}

.subject-stats {
  display: grid;
  grid-template-columns: repeat(3, 92px);
  gap: 10px;
}

.subject-stats span {
  min-height: 72px;
  display: grid;
  place-items: center;
  text-align: center;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--muted);
  background: var(--surface-2);
}

.subject-stats strong {
  display: block;
  color: var(--teal-dark);
  font-size: 24px;
  line-height: 1;
}

.mobile-tabs { display: none; }

.reader-layout {
  display: grid;
  grid-template-columns: minmax(280px, 24vw) minmax(0, 1fr);
  gap: 16px;
  align-items: start;
}

.outline-pane,
.pdf-viewer {
  position: sticky;
  top: calc(var(--header) + 16px);
  max-height: calc(100vh - var(--header) - 32px);
  overflow: auto;
  padding: 16px;
}

.outline-pane {
  display: grid;
  gap: 14px;
}

.side-section + .side-section {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.side-section label,
.side-section h2 {
  display: block;
  margin-bottom: 8px;
  font-size: 15px;
  font-weight: 800;
}

.outline-search {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 0 12px;
  outline-color: var(--teal);
}

.side-help {
  color: var(--muted);
  font-size: 13px;
}

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

.pdf-list li {
  display: grid;
  gap: 8px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}

.pdf-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.pdf-actions a,
.pdf-actions button,
.viewer-toolbar a {
  min-height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid #b7c8d8;
  border-radius: 6px;
  padding: 0 10px;
  background: white;
  color: #1f3f5b;
  text-decoration: none;
  cursor: pointer;
}

.pdf-actions button:hover,
.pdf-actions a:hover,
.viewer-toolbar a:hover {
  border-color: var(--teal);
  color: var(--teal-dark);
}

.toc-nav {
  display: grid;
  gap: 2px;
}

.toc-link {
  display: block;
  padding: 7px 8px;
  border-radius: 6px;
  color: #334155;
  text-decoration: none;
  font-size: 14px;
  line-height: 1.35;
}

.toc-l1 { font-weight: 800; }
.toc-l2 { padding-left: 18px; }
.toc-link:hover {
  background: var(--teal-soft);
  color: var(--teal-dark);
}

.outline-content {
  padding: clamp(18px, 3vw, 34px);
  overflow: hidden;
}

.outline-content h1 {
  margin-bottom: 14px;
  font-size: clamp(26px, 4vw, 36px);
}

.outline-content h2 {
  margin-top: 34px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.outline-content ul {
  margin: 12px 0 20px;
  padding: 0;
  list-style: none;
}

.outline-content li {
  margin: 8px 0;
  padding: 10px 12px;
  border-left: 3px solid var(--teal);
  border-radius: 0 6px 6px 0;
  background: #fbfdff;
}

.outline-content strong { color: var(--teal-dark); }

.outline-item.is-hidden { display: none; }

mark {
  background: #fde68a;
  color: inherit;
  padding: 0 2px;
  border-radius: 3px;
}

.pdf-viewer {
  display: grid;
  gap: 12px;
  min-height: calc(100vh - var(--header) - 32px);
  padding: 14px;
}

.viewer-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
}

.viewer-toolbar p {
  margin: 3px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.pdf-switcher {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 4px;
}

.pdf-switcher button {
  min-height: 38px;
  flex: 0 0 auto;
  max-width: 220px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 0 10px;
  background: white;
  color: #334155;
  cursor: pointer;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.pdf-switcher button:hover,
.pdf-switcher button.is-active {
  border-color: var(--teal);
  background: var(--teal-soft);
  color: var(--teal-dark);
}

#pdf-frame {
  width: 100%;
  height: calc(100vh - var(--header) - 168px);
  min-height: 620px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface-2);
}

.mobile-pdf-list {
  display: none;
}

.pdf-viewer > p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

@media (max-width: 1120px) {
  .reader-layout {
    grid-template-columns: 300px minmax(0, 1fr);
  }
}

@media (max-width: 860px) {
  :root { --header: 58px; }
  body { font-size: 15px; }
  .site-header {
    align-items: flex-start;
    flex-direction: column;
    gap: 8px;
    padding: 10px 14px;
  }
  .site-brand { min-height: 38px; }
  .top-nav {
    width: 100%;
    padding-bottom: 4px;
  }
  main {
    width: min(100% - 20px, 680px);
    padding-top: 14px;
  }
  .home-hero,
  .upload-guide,
  .file-maps,
  .subject-grid,
  .subject-header {
    grid-template-columns: 1fr;
  }
  .home-hero { padding: 22px; }
  .site-preview { min-height: 168px; padding: 18px; }
  .subject-link {
    grid-template-columns: 52px minmax(0, 1fr) 22px;
    min-height: 112px;
    padding: 16px;
  }
  .subject-token {
    width: 48px;
    height: 48px;
  }
  .subject-stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .subject-stats span { min-height: 62px; }
  .mobile-tabs {
    position: sticky;
    top: 104px;
    z-index: 15;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 6px;
    margin: 0 0 12px;
    padding: 8px;
    background: rgba(244, 246, 248, 0.96);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    backdrop-filter: blur(10px);
  }
  .tab-button {
    min-height: 42px;
    border: 1px solid var(--line);
    border-radius: 7px;
    background: white;
    color: #334155;
  }
  .tab-button.is-active {
    background: var(--teal);
    border-color: var(--teal);
    color: white;
  }
  .reader-layout {
    display: block;
  }
  .outline-pane,
  .pdf-viewer {
    position: static;
    max-height: none;
    margin-bottom: 12px;
    padding: 12px;
  }
  .outline-pane .search-section {
    display: block;
    border: 0;
    margin: 0 0 12px;
    padding: 0;
  }
  .mobile-panel {
    display: none;
  }
  .mobile-panel.is-active {
    display: block;
  }
  .outline-content {
    padding: 16px 12px;
  }
  .outline-content h2 {
    margin-top: 26px;
    padding-top: 14px;
    font-size: 19px;
  }
  .outline-content li {
    padding: 9px 10px;
    overflow-wrap: anywhere;
  }
  .pdf-list li {
    gap: 10px;
  }
  .pdf-actions a,
  .pdf-actions button {
    min-height: 42px;
    flex: 1 1 96px;
  }
  .pdf-actions button {
    display: none;
  }
  .pdf-viewer {
    min-height: 0;
  }
  .viewer-toolbar {
    display: grid;
  }
  .pdf-switcher {
    display: none;
  }
  #pdf-frame {
    height: 68vh;
    min-height: 420px;
  }
  .mobile-pdf-list {
    display: block;
  }
}

@media (max-width: 520px) {
  .subject-stats {
    grid-template-columns: 1fr;
  }
  .upload-guide,
  .file-map {
    padding: 18px 14px;
  }
  h1 { font-size: 28px; }
}

@media print {
  body { background: white; }
  .site-header,
  .outline-pane,
  .pdf-viewer,
  .mobile-tabs {
    display: none;
  }
  main {
    width: 100%;
    padding: 0;
  }
  .reader-layout { display: block; }
  .outline-content {
    border: 0;
    box-shadow: none;
    padding: 0;
  }
  .outline-content li {
    break-inside: avoid;
  }
}