:root {
  --bg: #0d1117;
  --sidebar: #010409;
  --card: #161b22;
  --card-hover: #1c2128;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #58a6ff;
  --accent-dim: rgba(88, 166, 255, 0.12);
  --success: #3fb950;
  --warning: #d29922;
  --border: #30363d;
  --latex-bg: #0d1117;
  --nav-width: 260px;
  --radius: 10px;
  --font: "PingFang SC", "Microsoft YaHei", "Segoe UI", system-ui, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  font-size: 15px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

.layout {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--nav-width);
  height: 100vh;
  background: var(--sidebar);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  z-index: 100;
  overflow-y: auto;
}

.sidebar-brand {
  padding: 20px 18px 16px;
  border-bottom: 1px solid var(--border);
}
.sidebar-brand .logo {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-bottom: 4px;
}
.sidebar-brand h1 {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
  line-height: 1.35;
}
.sidebar-brand .page-tag {
  display: inline-block;
  margin-top: 8px;
  font-size: 0.72rem;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--accent-dim);
  color: var(--accent);
}

.nav-switch {
  padding: 12px 14px;
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.nav-switch a {
  display: block;
  padding: 8px 12px;
  border-radius: 6px;
  font-size: 0.82rem;
  color: var(--muted);
  text-decoration: none;
  border: 1px solid transparent;
  transition: background 0.15s, color 0.15s;
}
.nav-switch a:hover { background: var(--card); color: var(--text); }
.nav-switch a.active {
  background: var(--accent-dim);
  color: var(--accent);
  border-color: rgba(88, 166, 255, 0.25);
}

.nav-section {
  padding: 12px 14px 20px;
  flex: 1;
}
.nav-section .nav-label {
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  padding: 8px 12px 6px;
}
.nav-section a {
  display: block;
  padding: 6px 12px;
  font-size: 0.84rem;
  color: var(--muted);
  text-decoration: none;
  border-radius: 6px;
  border-left: 2px solid transparent;
}
.nav-section a:hover {
  color: var(--text);
  background: var(--card);
}
.nav-section a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: var(--accent-dim);
}

.main {
  margin-left: var(--nav-width);
  flex: 1;
  padding: 32px 40px 64px;
  max-width: 920px;
}

.hero {
  margin-bottom: 28px;
}
.hero h2 {
  margin: 0 0 10px;
  font-size: 1.65rem;
  font-weight: 600;
  background: linear-gradient(135deg, var(--text) 0%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p { margin: 0; color: var(--muted); font-size: 0.95rem; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin-bottom: 16px;
}
.card h3 {
  margin: 0 0 12px;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}
.card h4 {
  margin: 16px 0 8px;
  font-size: 0.88rem;
  color: var(--accent);
  font-weight: 600;
}
.card p { margin: 0 0 10px; color: var(--muted); }
.card p:last-child { margin-bottom: 0; }
.card ul { margin: 8px 0 0; padding-left: 1.2em; color: var(--muted); }
.card li { margin: 4px 0; }

.section-title {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--muted);
  margin: 32px 0 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.map-compare {
  display: grid;
  gap: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 12px 0;
  font-size: 0.88rem;
}
.map-compare .row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border-bottom: 1px solid var(--border);
}
.map-compare .row:last-child { border-bottom: none; }
.map-compare .row.head {
  background: var(--sidebar);
  font-weight: 600;
  color: var(--text);
}
.map-compare .cell {
  padding: 10px 14px;
  color: var(--muted);
}
.map-compare .row.head .cell { color: var(--text); }
.map-compare .cell:first-child { border-right: 1px solid var(--border); }
.map-compare .match { color: var(--success); }

.latex-block {
  background: var(--latex-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px 20px;
  margin: 14px 0;
  overflow-x: auto;
  text-align: center;
}
.latex-block .caption {
  display: block;
  text-align: left;
  font-size: 0.78rem;
  color: var(--muted);
  margin-bottom: 10px;
}

.confirm-strip {
  background: linear-gradient(90deg, var(--accent-dim), transparent);
  border: 1px solid rgba(88, 166, 255, 0.2);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 24px;
}
.confirm-strip strong { color: var(--accent); }
.confirm-strip ul { margin: 8px 0 0; color: var(--muted); }

.pill-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 10px; }
.pill {
  font-size: 0.78rem;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--muted);
}

details.fold {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 10px;
  background: var(--card);
}
details.fold summary {
  cursor: pointer;
  padding: 14px 18px;
  font-weight: 500;
  color: var(--text);
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
}
details.fold summary::-webkit-details-marker { display: none; }
details.fold summary::after {
  content: "+";
  color: var(--accent);
  font-size: 1.1rem;
  font-weight: 300;
}
details.fold[open] summary::after { content: "−"; }
details.fold .fold-body {
  padding: 0 18px 16px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.9rem;
}
details.fold .fold-body ol, details.fold .fold-body ul {
  margin: 10px 0;
  padding-left: 1.2em;
}
details.fold .fold-body li { margin: 6px 0; }

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--accent-dim);
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 600;
  margin-right: 8px;
}

.tip {
  font-size: 0.85rem;
  padding: 10px 14px;
  border-radius: 8px;
  background: rgba(63, 185, 80, 0.08);
  border-left: 3px solid var(--success);
  color: var(--muted);
  margin-top: 10px;
}
.warn {
  background: rgba(210, 153, 34, 0.08);
  border-left-color: var(--warning);
}

footer.doc-foot {
  margin-top: 48px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  font-size: 0.8rem;
  color: var(--muted);
  text-align: center;
}

@media (max-width: 900px) {
  .sidebar { width: 220px; --nav-width: 220px; }
  .main { padding: 24px 20px 48px; }
  .map-compare .row { grid-template-columns: 1fr; }
  .map-compare .cell:first-child { border-right: none; border-bottom: 1px solid var(--border); }
}

@media print {
  .sidebar { display: none; }
  .main { margin-left: 0; max-width: 100%; }
  body { background: #fff; color: #000; }
  .card { break-inside: avoid; }
}