:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #6b6b6b;
  --accent: #c8102e;
  --border: #e6e6e6;
  --sidebar-bg: #fafafa;
  --quote-bg: #f5f5f0;
  --code-bg: #f4f4f4;
  --link: #0b5cad;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #15161a;
    --fg: #e7e7e7;
    --muted: #9a9a9a;
    --accent: #ff5a72;
    --border: #2a2c33;
    --sidebar-bg: #1b1d22;
    --quote-bg: #1f2128;
    --code-bg: #20232a;
    --link: #79b6ff;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--bg); color: var(--fg); }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Inter", "Helvetica Neue", Arial, sans-serif;
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
.layout { display: grid; grid-template-columns: 280px 1fr; min-height: 100vh; }
aside.toc {
  background: var(--sidebar-bg);
  border-right: 1px solid var(--border);
  padding: 28px 22px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}
aside.toc .brand { font-weight: 700; font-size: 15px; letter-spacing: 0.02em; }
aside.toc .brand a { color: var(--fg); text-decoration: none; }
aside.toc .brand small { display: block; color: var(--muted); font-weight: 400; font-size: 12px; margin-top: 2px; }
aside.toc ol { list-style: none; padding: 0; margin: 22px 0 0; counter-reset: c; }
aside.toc li { margin: 2px 0; }
aside.toc a {
  display: block; padding: 6px 10px; border-radius: 6px;
  color: var(--fg); text-decoration: none; font-size: 14px; line-height: 1.35;
}
aside.toc a:hover { background: var(--border); }
aside.toc a.active { background: var(--accent); color: #fff; }
aside.toc .section { font-size: 11px; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); margin: 22px 0 6px 10px; }
main { padding: 56px 64px 96px; max-width: 820px; }
main h1 { font-size: 34px; line-height: 1.2; margin: 0 0 8px; letter-spacing: -0.01em; }
main h2 { font-size: 24px; margin: 36px 0 12px; line-height: 1.25; }
main h3 { font-size: 19px; margin: 28px 0 10px; color: var(--fg); }
main p { margin: 0 0 16px; }
main a { color: var(--link); }
main hr { border: none; border-top: 1px solid var(--border); margin: 32px 0; }
main blockquote {
  margin: 18px 0; padding: 14px 18px;
  background: var(--quote-bg); border-left: 3px solid var(--accent); border-radius: 4px;
  font-style: italic; color: var(--fg);
}
main blockquote p { margin: 0; }
main code { background: var(--code-bg); padding: 2px 6px; border-radius: 4px; font-size: 0.9em; }
main pre { background: var(--code-bg); padding: 14px 16px; border-radius: 6px; overflow-x: auto; font-size: 0.9em; }
main table { border-collapse: collapse; width: 100%; margin: 18px 0; font-size: 15px; }
main th, main td { border: 1px solid var(--border); padding: 8px 12px; text-align: left; }
main th { background: var(--sidebar-bg); font-weight: 600; }
main ul, main ol { padding-left: 22px; margin: 0 0 16px; }
main li { margin: 4px 0; }
main strong { font-weight: 600; }
.nav-buttons { display: flex; justify-content: space-between; gap: 12px; margin-top: 56px; padding-top: 24px; border-top: 1px solid var(--border); }
.nav-buttons a {
  display: inline-block; padding: 10px 16px; border: 1px solid var(--border);
  border-radius: 6px; text-decoration: none; color: var(--fg); font-size: 14px;
}
.nav-buttons a:hover { background: var(--sidebar-bg); }
.nav-buttons .placeholder { visibility: hidden; }
.footer-note { color: var(--muted); font-size: 13px; margin-top: 32px; }

.mobile-toggle { display: none; }
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  aside.toc {
    position: fixed; left: -300px; width: 280px; height: 100vh; z-index: 50;
    transition: left 0.2s ease-out;
  }
  aside.toc.open { left: 0; }
  main { padding: 24px 22px 64px; }
  main h1 { font-size: 28px; }
  .mobile-toggle {
    display: block; position: fixed; top: 12px; right: 12px; z-index: 60;
    background: color-mix(in srgb, var(--bg) 78%, transparent);
    backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
    color: var(--fg); border: 1px solid var(--border); border-radius: 8px;
    padding: 7px 12px; font-size: 13px; line-height: 1; cursor: pointer;
    box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  }
  .mobile-toggle:active { background: var(--sidebar-bg); }
}