:root {
  --bg: #f6f7fb;
  --paper: rgba(255, 255, 255, .78);
  --paper-solid: #ffffff;
  --paper-soft: rgba(248, 250, 252, .74);
  --ink: #020617;
  --muted: #64748b;
  --line: rgba(203, 213, 225, .72);
  --brand: #0284c7;
  --brand-2: #06b6d4;
  --accent: #6366f1;
  --soft: rgba(224, 242, 254, .72);
  --soft-2: rgba(240, 253, 250, .72);
  --danger: #b42318;
  --code-bg: #0f172a;
  --code-ink: #e5e7eb;
  --shadow: 0 24px 72px rgba(15, 23, 42, .10);
  --shadow-soft: 0 14px 42px rgba(15, 23, 42, .07);
  --radius: 24px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 16% 12%, rgba(96,165,250,.18), transparent 28%),
    radial-gradient(circle at 82% 18%, rgba(45,212,191,.13), transparent 26%),
    linear-gradient(180deg, #fbfcff 0%, #eef3f8 100%);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", Arial, sans-serif;
  line-height: 1.78;
  overflow-x: hidden;
}
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: -1;
  opacity: .42;
  background-image:
    linear-gradient(rgba(15,23,42,.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(15,23,42,.055) 1px, transparent 1px);
  background-size: 88px 88px;
}
a { color: var(--brand); }
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  width: 0;
  height: 3px;
  z-index: 50;
  background: linear-gradient(90deg, #8b5cf6, #0ea5e9, #22d3ee);
}
.topbar {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  max-width: 1500px;
  margin: 0 auto 16px;
  padding: 0 20px;
}
.reader-topbar {
  padding-top: 18px;
}
.home-link, .continue-button {
  border: 1px solid rgba(203, 213, 225, .78);
  color: #334155;
  background: rgba(255,255,255,.68);
  border-radius: 999px;
  padding: 7px 12px;
  text-decoration: none;
  font: inherit;
  font-size: 14px;
  font-weight: 800;
  cursor: pointer;
  box-shadow: 0 12px 30px rgba(15, 23, 42, .08);
  backdrop-filter: blur(18px) saturate(160%);
}
.home-link:hover, .continue-button:hover {
  border-color: rgba(56, 189, 248, .56);
  color: #020617;
  background: rgba(255,255,255,.86);
}
.book-landing {
  padding: 18px 0 0;
  color: var(--ink);
}
.hero-card {
  max-width: 1500px;
  margin: 0 auto;
  padding: 30px 42px 26px;
  position: relative;
  overflow: hidden;
  border: 1px solid rgba(255,255,255,.82);
  border-radius: 28px;
  background:
    radial-gradient(circle at 12% 12%, rgba(56,189,248,.12), transparent 34%),
    radial-gradient(circle at 88% 18%, rgba(99,102,241,.10), transparent 34%),
    rgba(255,255,255,.72);
  box-shadow: 0 34px 96px rgba(15,23,42,.13);
  backdrop-filter: blur(24px) saturate(165%);
}
.hero-card::after {
  content: "";
  position: absolute;
  right: -110px;
  top: -132px;
  width: 280px;
  height: 280px;
  border-radius: 50%;
  background: rgba(14,165,233,.08);
}
.eyebrow, .section-label {
  margin: 0 0 8px;
  color: #38bdf8;
  font-size: 13px;
  letter-spacing: .24em;
  text-transform: uppercase;
  font-weight: 800;
}
.hero-card .eyebrow { color: #38bdf8; }
.hero-card h1 {
  max-width: 1160px;
  margin: 0;
  color: #020617;
  font-size: clamp(34px, 4.2vw, 52px);
  font-weight: 950;
  line-height: 1.04;
  letter-spacing: 0;
  text-wrap: balance;
}
.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 14px;
}
.primary-action, .secondary-action {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 7px 13px;
  border-radius: 13px;
  text-decoration: none;
  font-weight: 850;
}
.primary-action {
  background: linear-gradient(90deg, #8b5cf6, #0ea5e9, #67e8f9);
  color: #fff;
  box-shadow: 0 18px 48px rgba(56,189,248,.24);
}
.secondary-action {
  border: 1px solid rgba(203, 213, 225, .78);
  color: #475569;
  background: rgba(255,255,255,.62);
}
.book-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  max-width: 680px;
  margin: 16px 0 0;
}
.book-stats div {
  border: 1px solid rgba(203, 213, 225, .72);
  background: rgba(255,255,255,.62);
  border-radius: 14px;
  padding: 8px 12px;
}
.book-stats dt { margin: 0; color: var(--muted); font-size: 12px; }
.book-stats dd { margin: 4px 0 0; color: var(--ink); font-weight: 900; }
.landing-main {
  max-width: 1500px;
  margin: 0 auto;
  padding: 28px 20px 80px;
}
.intro-panel, .visual-panel, .index-group {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  backdrop-filter: blur(22px) saturate(160%);
}
.intro-panel {
  padding: 34px;
}
.visual-panel {
  display: grid;
  grid-template-columns: minmax(0, .8fr) minmax(0, 1.2fr);
  gap: 22px;
  margin-top: 22px;
  padding: 34px;
}
.visual-copy h2, .index-group h2 {
  margin: 0 0 8px;
  font-size: 28px;
  font-weight: 950;
  line-height: 1.25;
}
.visual-copy p { margin: 0; color: var(--muted); }
.agent-bridge {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  align-items: center;
}
.bridge-source, .bridge-outcome, .bridge-core {
  border-radius: 18px;
  border: 1px solid var(--line);
  padding: 16px;
  text-align: center;
  font-weight: 900;
}
.bridge-source { background: rgba(248,250,252,.74); color: #334155; }
.bridge-core {
  grid-column: 1 / -1;
  background: linear-gradient(135deg, #0ea5e9, #06b6d4);
  color: #fff;
  font-size: 20px;
}
.bridge-outcome { background: var(--soft-2); color: var(--brand-2); }
.layer-grid {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
}
.layer-card, .city-zone {
  text-decoration: none;
  color: var(--ink);
  border: 1px solid var(--line);
  background: var(--paper-soft);
  border-radius: 18px;
  padding: 16px;
  box-shadow: var(--shadow-soft);
}
.layer-card:hover, .city-zone:hover { border-color: rgba(56,189,248,.62); background: rgba(255,255,255,.86); }
.city-map {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}
.city-zone strong { display: block; margin-bottom: 5px; color: var(--brand); }
.city-zone span { color: var(--muted); font-size: 14px; }
.full-index {
  margin-top: 22px;
}
.index-group {
  margin-top: 16px;
  padding: 24px;
}
.group-head {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 14px;
  align-items: center;
  border-bottom: 1px solid var(--line);
  padding-bottom: 14px;
  margin-bottom: 14px;
}
.group-number {
  display: inline-grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--soft);
  color: var(--brand);
  font-weight: 900;
}
.group-head p { margin: 0; color: var(--muted); }
.chapter-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}
.chapter-grid a {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 16px;
  border-radius: 16px;
  color: var(--ink);
  text-decoration: none;
  background: rgba(248,250,252,.70);
  border: 1px solid rgba(226,232,240,.72);
}
.chapter-grid a:hover { border-color: rgba(56,189,248,.62); background: var(--soft); color: var(--brand); }
.chapter-grid small { flex: 0 0 auto; color: var(--muted); }
.chapter-grid .part-overview-card {
  grid-column: 1 / -1;
  align-items: center;
  padding: 16px 18px;
  background: linear-gradient(135deg, rgba(224,242,254,.86), rgba(255,255,255,.80));
  border: 1px solid rgba(125,211,252,.48);
  border-left: 5px solid #0ea5e9;
  color: var(--brand);
  font-weight: 900;
}
.chapter-grid .part-overview-card span {
  font-size: 18px;
  line-height: 1.35;
}
.chapter-grid .part-overview-card small {
  color: var(--brand);
  background: rgba(22, 63, 99, .08);
  border-radius: 999px;
  padding: 4px 9px;
}
.chapter-grid .part-overview-card:hover {
  border-color: #9cc4e4;
  background: var(--soft);
}
.reader-shell {
  display: grid;
  grid-template-columns: 310px minmax(0, 1fr) 250px;
  gap: 22px;
  max-width: 1500px;
  margin: 0 auto;
  padding: 24px 20px 72px;
}
.reader-shell.toc-empty {
  grid-template-columns: 310px minmax(0, 1fr);
  max-width: 1260px;
}
.reader-shell.toc-empty .chapter-toc {
  display: none;
}
.book-sidebar, .chapter-toc {
  position: sticky;
  top: 16px;
  align-self: start;
  max-height: calc(100vh - 32px);
  overflow: auto;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(22px) saturate(160%);
}
.book-title-link {
  display: block;
  color: var(--ink);
  text-decoration: none;
  font-weight: 900;
  margin-bottom: 12px;
  line-height: 1.35;
}
.sidebar-group {
  border-top: 1px solid var(--line);
  padding: 8px 0;
}
.sidebar-group-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 0;
  color: var(--muted);
  text-decoration: none;
  font-size: 13px;
  line-height: 1.35;
}
.sidebar-group-link:hover { color: var(--brand); }
.sidebar-group-link span {
  color: #98a2b3;
  font-size: 12px;
}
.sidebar-group summary {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  cursor: pointer;
  color: #0f3f62;
  font-weight: 800;
  line-height: 1.4;
  list-style: none;
  border-radius: 9px;
  padding: 7px 8px;
}
.sidebar-group summary::-webkit-details-marker,
.sidebar-subgroup summary::-webkit-details-marker {
  display: none;
}
.sidebar-group summary::marker,
.sidebar-subgroup summary::marker {
  content: "";
}
.sidebar-group summary::before,
.sidebar-subgroup summary::before {
  content: "";
  flex: 0 0 auto;
  width: 0;
  height: 0;
  margin-top: .42em;
  border-top: 5px solid transparent;
  border-bottom: 5px solid transparent;
  border-left: 6px solid currentColor;
  opacity: .82;
  transition: transform .18s ease;
}
.sidebar-group[open] > summary::before,
.sidebar-subgroup[open] > summary::before {
  transform: rotate(90deg);
}
.sidebar-group summary:hover,
.sidebar-subgroup summary:hover {
  background: rgba(224, 242, 254, .54);
}
.sidebar-subgroup {
  margin: 5px 0 0 8px;
  padding: 4px 0 4px 10px;
  border-left: 1px solid var(--line);
}
.sidebar-subgroup summary {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  cursor: pointer;
  color: var(--muted);
  font-size: 13px;
  font-weight: 760;
  line-height: 1.4;
  list-style: none;
  border-radius: 9px;
  padding: 7px 8px;
}
.sidebar-subgroup[open] > summary {
  color: var(--brand);
}
.sidebar-group.is-active > summary,
.sidebar-subgroup.is-active > summary,
.sidebar-group[data-user-active="true"] > summary,
.sidebar-subgroup[data-user-active="true"] > summary {
  background: var(--soft);
  border-radius: 9px;
  color: var(--brand);
  box-shadow: inset 3px 0 0 #0ea5e9;
}
.sidebar-subgroup.is-active,
.sidebar-subgroup[data-user-active="true"] {
  border-left-color: rgba(56,189,248,.62);
}
.summary-title {
  flex: 1 1 auto;
  min-width: 0;
}
.summary-count {
  flex: 0 0 auto;
  margin-left: auto;
  color: #98a2b3;
  font-size: 12px;
}
.sidebar-node-links {
  margin-top: 4px;
}
.sidebar-link {
  display: grid;
  gap: 2px;
  padding: 8px 9px;
  margin-top: 3px;
  color: var(--muted);
  text-decoration: none;
  border-radius: 9px;
  font-size: 14px;
  line-height: 1.35;
}
.sidebar-link small { color: #98a2b3; }
.sidebar-link:hover, .sidebar-link.active {
  background: var(--soft);
  color: var(--brand);
}
.chapter-main {
  min-width: 0;
}
.chapter-hero {
  background:
    radial-gradient(circle at 15% 10%, rgba(56,189,248,.14), transparent 36%),
    radial-gradient(circle at 88% 18%, rgba(99,102,241,.10), transparent 34%),
    rgba(255,255,255,.74);
  color: var(--ink);
  border: 1px solid rgba(255,255,255,.82);
  border-radius: 28px;
  padding: 30px 32px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(22px) saturate(165%);
}
.crumb {
  color: var(--brand);
  text-decoration: none;
  font-weight: 800;
  font-size: 14px;
}
.chapter-group {
  margin: 10px 0 5px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.45;
}
.chapter-hero h1 {
  margin: 0;
  color: #020617;
  font-size: clamp(30px, 4vw, 54px);
  font-weight: 950;
  line-height: 1.12;
  letter-spacing: 0;
}
.chapter-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}
.chapter-meta span {
  border: 1px solid rgba(203, 213, 225, .72);
  background: rgba(255,255,255,.62);
  border-radius: 999px;
  padding: 4px 9px;
  font-size: 12px;
  color: var(--muted);
}
.prose {
  font-size: 17px;
  line-height: 1.88;
}
.chapter-prose {
  margin-top: 22px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 38px;
  box-shadow: var(--shadow-soft);
  backdrop-filter: blur(22px) saturate(160%);
}
.prose h2, .prose h3, .prose h4, .prose h5 {
  color: #020617;
  line-height: 1.32;
  scroll-margin-top: 20px;
  font-weight: 950;
}
.prose h2 { margin: 34px 0 14px; font-size: 28px; border-bottom: 1px solid var(--line); padding-bottom: 10px; }
.prose h3 { margin: 28px 0 12px; font-size: 23px; }
.prose h4 { margin: 22px 0 10px; font-size: 19px; color: #0f172a; }
.prose h5 { margin: 18px 0 8px; font-size: 16px; }
.heading-anchor {
  opacity: 0;
  margin-right: 8px;
  text-decoration: none;
}
.prose h2:hover .heading-anchor,
.prose h3:hover .heading-anchor,
.prose h4:hover .heading-anchor { opacity: .55; }
.prose p { margin: 12px 0; }
.prose blockquote {
  margin: 18px 0;
  padding: 16px 18px;
  border-left: 5px solid #22d3ee;
  background: rgba(224,242,254,.52);
  border-radius: 12px;
  color: #0f172a;
}
.prose ul, .prose ol { padding-left: 1.45em; }
.prose li { margin: 5px 0; }
.prose img {
  max-width: 100%;
  height: auto;
  border-radius: 12px;
  border: 1px solid var(--line);
}
.prose code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  background: rgba(226,232,240,.78);
  padding: 2px 5px;
  border-radius: 6px;
  font-size: .92em;
}
.code-block {
  margin: 18px 0;
  background: var(--code-bg);
  border-radius: 14px;
  overflow: hidden;
  border: 1px solid #1f2937;
}
.code-block figcaption {
  padding: 8px 14px;
  color: #9ca3af;
  background: #111827;
  font-size: 12px;
}
.code-block pre {
  margin: 0;
  padding: 16px;
  overflow-x: auto;
  color: var(--code-ink);
  line-height: 1.55;
  font-size: 13px;
}
.code-block code { background: transparent; color: inherit; padding: 0; }
.table-wrap {
  overflow-x: auto;
  margin: 18px 0;
  border: 1px solid var(--line);
  border-radius: 12px;
}
table {
  width: 100%;
  border-collapse: collapse;
  min-width: 620px;
}
th, td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
th { background: rgba(248,250,252,.82); text-align: left; color: #334155; }
tr:last-child td { border-bottom: none; }
.chapter-toc h2 {
  margin: 0 0 10px;
  font-size: 15px;
}
.chapter-toc a {
  display: block;
  text-decoration: none;
  color: var(--muted);
  border-radius: 8px;
  padding: 6px 8px;
  font-size: 13px;
  line-height: 1.35;
}
.chapter-toc a:hover, .chapter-toc a.active { background: var(--soft); color: var(--brand); }
.toc-level-3 { padding-left: 18px !important; }
.toc-level-4 { padding-left: 30px !important; }
.empty-toc { color: var(--muted); font-size: 13px; }
.chapter-pager {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 20px;
}
.pager-link {
  display: grid;
  gap: 5px;
  text-decoration: none;
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 16px;
  box-shadow: var(--shadow-soft);
  backdrop-filter: blur(18px) saturate(160%);
}
.pager-link span { color: var(--muted); font-size: 13px; }
.pager-link.next { text-align: right; }
.pager-link:hover { border-color: rgba(56,189,248,.62); background: var(--soft); }
.sidebar-toggle {
  display: none;
  position: fixed;
  z-index: 60;
  right: 14px;
  bottom: 14px;
  border: none;
  border-radius: 999px;
  padding: 10px 15px;
  background: #0f172a;
  color: #fff;
  box-shadow: var(--shadow);
}
body.sidebar-open {
  overflow: hidden;
}
@media (max-width: 1180px) {
  .reader-shell { grid-template-columns: 260px minmax(0, 1fr); }
  .chapter-toc { display: none; }
}
@media (max-width: 860px) {
  .book-stats, .visual-panel, .chapter-grid, .city-map, .layer-grid, .chapter-pager {
    grid-template-columns: 1fr;
  }
  .group-head { grid-template-columns: auto 1fr; }
  .group-head p { grid-column: 2; }
  .reader-shell { display: block; padding: 14px 12px 80px; }
  .book-sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    width: min(84vw, 340px);
    height: 100vh;
    height: 100dvh;
    max-height: 100vh;
    max-height: 100dvh;
    overflow-x: hidden;
    overflow-y: auto;
    overscroll-behavior: contain;
    -webkit-overflow-scrolling: touch;
    touch-action: pan-y;
    padding-bottom: calc(18px + env(safe-area-inset-bottom));
    z-index: 55;
    border-radius: 0;
    transform: translateX(-105%);
    transition: transform .18s ease;
  }
  .book-sidebar.open { transform: translateX(0); }
  .sidebar-toggle { display: inline-flex; }
  .chapter-hero { padding: 18px 18px; border-radius: 12px; }
  .chapter-hero h1 { font-size: clamp(22px, 7vw, 30px); }
  .chapter-prose { padding: 22px; }
  .topbar { padding: 0 14px; }
  .hero-card { padding: 24px 16px 20px; }
  .landing-main { padding: 20px 14px 70px; }
  .intro-panel, .visual-panel, .index-group { padding: 20px; }
}
@media print {
  .book-sidebar, .chapter-toc, .sidebar-toggle, .progress-bar, .topbar, .chapter-pager { display: none !important; }
  .reader-shell { display: block; padding: 0; }
  .chapter-hero, .chapter-prose { box-shadow: none; }
}