:root {
  --bg: #ffffff;
  --fg: #1f2328;
  --muted: #57606a;
  --border: #d0d7de;
  --accent: #0969da;
  --code-bg: #f6f8fa;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --fg: #e6edf3;
    --muted: #9198a1;
    --border: #30363d;
    --accent: #2f81f7;
    --code-bg: #161b22;
  }
}

/* Light/dark toggle */
html[data-theme="dark"] {
  --bg: #0d1117;
  --fg: #e6edf3;
  --muted: #9198a1;
  --border: #30363d;
  --accent: #2f81f7;
  --code-bg: #161b22;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  color: var(--fg);
  background: var(--bg);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", system-ui, sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

.site-header {
  position: sticky; top: 0; z-index: 10;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  backdrop-filter: saturate(120%) blur(6px);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand-title { font-size: 22px; font-weight: 700; }
.brand-subtitle { color: var(--muted); font-size: 13px; }
.theme-toggle { border: 1px solid var(--border); background: transparent; color: var(--fg); border-radius: 8px; padding: 6px 10px; cursor: pointer; }

.layout { display: grid; grid-template-columns: 260px 1fr; gap: 28px; padding: 28px 20px; }

.toc { position: sticky; top: 80px; align-self: start; height: max-content; }
.toc-title { font-weight: 600; margin-bottom: 8px; }
.toc nav, #toc { display: block; border-left: 2px solid var(--border); padding-left: 12px; }
.toc a { color: var(--muted); text-decoration: none; display: block; padding: 4px 0; font-size: 14px; }
.toc a.active { color: var(--accent); font-weight: 600; }

.content { min-width: 0; }
.content h1 { font-size: 32px; margin: 0.2em 0 0.6em; }
.content h2 { font-size: 22px; margin-top: 1.6em; border-bottom: 1px solid var(--border); padding-bottom: 6px; }
.content h3 { font-size: 18px; margin-top: 1.2em; }
.content p { margin: 0.6em 0 0.8em; }
.content a { color: var(--accent); text-decoration: none; }
.content a:hover { text-decoration: underline; }
.content code { background: var(--code-bg); padding: 2px 6px; border-radius: 6px; font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; font-size: 0.95em; }
.content pre { background: var(--code-bg); padding: 12px 14px; border-radius: 8px; overflow: auto; }
.content ul { padding-left: 1.2em; }
.content li { margin: 4px 0; }

.site-footer { border-top: 1px solid var(--border); margin-top: 28px; padding: 18px 0; color: var(--muted); }

/* Responsive */
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .toc { position: relative; top: 0; }
}

/* Print styles */
@media print {
  .site-header, .site-footer, .theme-toggle, .toc { display: none; }
  .container { max-width: none; padding: 0; }
  .content h2 { border: none; }
}