:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --fg: #1a2233;
  --fg-muted: #5b6577;
  --border: #e4e8f0;
  --accent: #2563eb;
  --code-bg: #f3f5f9;
  --nav-bg: #f8f9fc;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --fg: #e6edf3;
    --fg-muted: #9aa7bd;
    --border: #232a35;
    --accent: #6ea8fe;
    --code-bg: #161b22;
    --nav-bg: #10141c;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--fg);
  background: var(--bg);
  display: flex;
  min-height: 100vh;
}
.site-header {
  position: sticky;
  top: 0;
  padding: 0.9rem 1.25rem;
  font-weight: 700;
  border-bottom: 1px solid var(--border);
  background: var(--nav-bg);
}
.site-header a { color: inherit; text-decoration: none; }
nav.sidebar {
  width: 260px;
  flex-shrink: 0;
  background: var(--nav-bg);
  border-right: 1px solid var(--border);
  height: 100vh;
  overflow-y: auto;
  position: sticky;
  top: 0;
}
.nav-list { list-style: none; margin: 0; padding: 0 0 1.5rem; }
.nav-root { padding-top: 0.5rem; }
.nav-list .nav-list { padding: 0.15rem 0 0.5rem 0.9rem; }
.nav-section-title, .nav-list a {
  display: block;
  padding: 0.35rem 1.1rem;
  font-size: 0.9rem;
  color: var(--fg);
  text-decoration: none;
}
.nav-section-title { font-weight: 700; color: var(--fg-muted); text-transform: uppercase; font-size: 0.75rem; letter-spacing: 0.04em; }
a.nav-section-title { color: var(--fg); text-transform: none; font-weight: 600; font-size: 0.9rem; letter-spacing: normal; }
.nav-list a:hover { background: var(--border); border-radius: 0.35rem; }
.nav-list a.active { color: var(--accent); font-weight: 600; background: var(--border); border-radius: 0.35rem; }
main {
  flex: 1;
  min-width: 0;
  padding: 2.5rem clamp(1.25rem, 4vw, 4rem);
  max-width: 860px;
}
main h1 { font-size: 1.9rem; margin-top: 0; }
main h2 { margin-top: 2.2rem; border-top: 1px solid var(--border); padding-top: 1.5rem; }
main :first-child { margin-top: 0; }
main pre {
  background: var(--code-bg);
  padding: 1rem;
  border-radius: 0.5rem;
  overflow-x: auto;
  border: 1px solid var(--border);
}
main code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 0.9em; }
main :not(pre) > code { background: var(--code-bg); padding: 0.15em 0.4em; border-radius: 0.3em; }
main table { border-collapse: collapse; width: 100%; display: block; overflow-x: auto; }
main th, main td { border: 1px solid var(--border); padding: 0.5rem 0.75rem; text-align: left; }
main a { color: var(--accent); }
main img { max-width: 100%; }
main blockquote { border-left: 3px solid var(--accent); margin: 1rem 0; padding: 0.25rem 1rem; color: var(--fg-muted); }
footer.page-footer { margin-top: 3rem; padding-top: 1rem; border-top: 1px solid var(--border); color: var(--fg-muted); font-size: 0.85rem; }
@media (max-width: 780px) {
  body { flex-direction: column; }
  nav.sidebar { width: 100%; height: auto; position: static; border-right: none; border-bottom: 1px solid var(--border); }
}