:root {
  --bg: #ffffff;
  --fg: #111827;
  --muted: #6b7280;
  --line: #e5e7eb;
  --brand: #2563eb;
  --brand-soft: #eff6ff;
  --code-bg: #0f172a;
  --code-fg: #e5e7eb;
  --card: #ffffff;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.75;
}
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }
.topbar {
  height: 64px;
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: center;
  padding: 0 28px;
  gap: 28px;
  position: sticky;
  top: 0;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(12px);
  z-index: 20;
}
.brand { font-weight: 800; color: var(--fg); font-size: 18px; }
.nav { display: flex; gap: 20px; flex-wrap: wrap; }
.nav a { color: #374151; font-weight: 600; }
.layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  min-height: calc(100vh - 64px);
}
.sidebar {
  border-right: 1px solid var(--line);
  padding: 28px 22px;
  position: sticky;
  top: 64px;
  height: calc(100vh - 64px);
  overflow-y: auto;
}
.sidebar h3 {
  font-size: 13px;
  color: var(--muted);
  margin: 20px 0 8px;
  text-transform: uppercase;
  letter-spacing: .06em;
}
.sidebar a {
  display: block;
  padding: 8px 12px;
  color: #374151;
  border-radius: 10px;
  margin: 3px 0;
}
.sidebar a.active, .sidebar a:hover {
  background: var(--brand-soft);
  color: var(--brand);
  text-decoration: none;
}
.content {
  max-width: 980px;
  width: 100%;
  padding: 44px 56px 80px;
}
.hero {
  padding: 48px;
  border: 1px solid var(--line);
  border-radius: 28px;
  background:
    radial-gradient(circle at 70% 20%, #dbeafe 0, transparent 35%),
    linear-gradient(135deg, #fff, #f8fafc);
}
.hero h1 {
  font-size: 52px;
  line-height: 1.08;
  margin: 0 0 18px;
  letter-spacing: -.04em;
}
.hero p { color: #4b5563; font-size: 18px; margin: 0 0 24px; }
.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border-radius: 999px;
  background: var(--brand-soft);
  color: var(--brand);
  padding: 6px 12px;
  font-weight: 700;
  font-size: 13px;
  margin-bottom: 18px;
}
.btns { display: flex; gap: 12px; flex-wrap: wrap; }
.btn {
  display: inline-block;
  padding: 11px 18px;
  border-radius: 14px;
  background: var(--brand);
  color: white;
  font-weight: 700;
}
.btn.secondary {
  background: #f3f4f6;
  color: #111827;
}
.btn:hover { text-decoration: none; opacity: .92; }
h1 { font-size: 42px; line-height: 1.15; margin: 0 0 24px; letter-spacing: -.03em; }
h2 { font-size: 26px; margin-top: 42px; padding-top: 8px; }
h3 { font-size: 20px; margin-top: 28px; }
p { margin: 14px 0; }
.lead { color: #4b5563; font-size: 18px; }
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 16px;
  margin: 28px 0;
}
.card {
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 20px;
  background: var(--card);
  box-shadow: 0 8px 30px rgba(15, 23, 42, .04);
}
.card h3 { margin-top: 0; }
code {
  background: #f3f4f6;
  color: #111827;
  border-radius: 6px;
  padding: 2px 6px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
pre {
  background: var(--code-bg);
  color: var(--code-fg);
  border-radius: 18px;
  padding: 18px 20px;
  overflow: auto;
  line-height: 1.55;
  margin: 18px 0;
}
pre code { background: transparent; color: inherit; padding: 0; }
.callout {
  border-left: 4px solid var(--brand);
  background: var(--brand-soft);
  padding: 14px 18px;
  border-radius: 12px;
  margin: 18px 0;
}
table {
  width: 100%;
  border-collapse: collapse;
  border: 1px solid var(--line);
  border-radius: 14px;
  overflow: hidden;
  display: table;
}
th, td {
  border-bottom: 1px solid var(--line);
  padding: 12px 14px;
  text-align: left;
}
th { background: #f9fafb; }
.footer {
  border-top: 1px solid var(--line);
  margin-top: 54px;
  padding-top: 20px;
  color: var(--muted);
  font-size: 14px;
}
@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { position: static; height: auto; border-right: 0; border-bottom: 1px solid var(--line); }
  .content { padding: 32px 22px 64px; }
  .hero { padding: 32px 24px; }
  .hero h1 { font-size: 38px; }
  .topbar { height: auto; min-height: 64px; align-items: flex-start; padding: 18px 20px; flex-direction: column; gap: 10px; }
}