:root {
  --bg: #ffffff;
  --bg-soft: #f7f8fa;
  --text: #1c2024;
  --muted: #5b6470;
  --border: #e6e8ec;
  --accent: #5b4bf5;
  --accent-soft: #efedff;
  --code-bg: #f4f5f7;
  --sidebar-w: 280px;
  --topbar-h: 56px;
  --maxw: 820px;
  font-synthesis: none;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115; --bg-soft: #161922; --text: #e6e8ec; --muted: #9aa4b2;
    --border: #262b36; --accent: #8a7dff; --accent-soft: #1d2030; --code-bg: #1a1e27;
  }
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Topbar */
.topbar {
  position: sticky; top: 0; z-index: 20; height: var(--topbar-h);
  display: flex; align-items: center; gap: 16px; padding: 0 20px;
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--border);
}
.topbar .brand { font-weight: 700; font-size: 18px; color: var(--text); }
.topbar .brand span { color: var(--accent); }
.topbar .brand em { font-style: normal; font-weight: 500; color: var(--muted); font-size: 14px; }
.topbar #filter {
  margin-left: auto; width: 220px; max-width: 40vw; padding: 7px 12px;
  border: 1px solid var(--border); border-radius: 8px; background: var(--bg-soft);
  color: var(--text); font-size: 14px;
}
.topbar .gh { color: var(--muted); font-size: 14px; white-space: nowrap; }
.topbar #menu { display: none; background: none; border: 0; font-size: 22px; color: var(--text); cursor: pointer; }

/* Layout */
.layout { display: flex; align-items: flex-start; }
.sidebar {
  position: sticky; top: var(--topbar-h); align-self: flex-start;
  width: var(--sidebar-w); flex: 0 0 var(--sidebar-w);
  height: calc(100vh - var(--topbar-h)); overflow-y: auto;
  padding: 24px 16px 60px; border-right: 1px solid var(--border);
}
.nav-group { margin-bottom: 6px; }
.nav-group > summary {
  list-style: none; cursor: pointer; user-select: none;
  margin: 0 0 4px; padding: 6px 10px; border-radius: 7px;
  font-size: 12px; letter-spacing: .06em; text-transform: uppercase; color: var(--muted);
  display: flex; align-items: center; gap: 6px;
}
.nav-group > summary::-webkit-details-marker { display: none; }
.nav-group > summary::before {
  content: "▸"; font-size: 10px; color: var(--muted); transition: transform .15s;
}
.nav-group[open] > summary::before { transform: rotate(90deg); }
.nav-group > summary:hover { background: var(--bg-soft); color: var(--text); }
.nav-group ul { list-style: none; margin: 0 0 10px; padding: 0; }
.nav-group li a {
  display: block; padding: 6px 10px; border-radius: 7px; color: var(--text);
  font-size: 14.5px;
}
.nav-group li a:hover { background: var(--bg-soft); text-decoration: none; }
.nav-group li a.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }

/* Content */
.content { flex: 1 1 auto; min-width: 0; padding: 40px 48px 100px; }
.md { max-width: var(--maxw); margin: 0 auto; }
.md h1 { font-size: 32px; line-height: 1.2; margin: 0 0 18px; letter-spacing: -.02em; }
.md h2 { font-size: 23px; margin: 44px 0 14px; padding-bottom: 7px; border-bottom: 1px solid var(--border); letter-spacing: -.01em; }
.md h3 { font-size: 18px; margin: 30px 0 10px; }
.md h2 .anchor, .md h3 .anchor {
  float: left; margin-left: -22px; width: 22px; color: var(--border);
  opacity: 0; text-decoration: none; font-weight: 400;
}
.md h2:hover .anchor, .md h3:hover .anchor { opacity: 1; color: var(--accent); }
.md p, .md li { color: var(--text); }
.md a { font-weight: 500; }
.md code {
  background: var(--code-bg); padding: 2px 6px; border-radius: 5px;
  font: 13.5px/1.5 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
.md pre {
  background: var(--code-bg); border: 1px solid var(--border); border-radius: 10px;
  padding: 16px 18px; overflow-x: auto; margin: 16px 0;
}
.md pre code { background: none; padding: 0; font-size: 13px; }
.md blockquote {
  margin: 16px 0; padding: 4px 18px; border-left: 3px solid var(--accent);
  background: var(--bg-soft); border-radius: 0 8px 8px 0; color: var(--muted);
}
.md table { border-collapse: collapse; width: 100%; margin: 18px 0; font-size: 14.5px; display: block; overflow-x: auto; }
.md th, .md td { border: 1px solid var(--border); padding: 8px 12px; text-align: left; }
.md th { background: var(--bg-soft); font-weight: 600; }
.md tr:nth-child(even) td { background: var(--bg-soft); }
.md hr { border: 0; border-top: 1px solid var(--border); margin: 36px 0; }
.md img { max-width: 100%; }
.md ul, .md ol { padding-left: 24px; }
.md li { margin: 4px 0; }

/* Home */
.home .tag { font-size: 16px; color: var(--muted); font-weight: 500; vertical-align: middle; }
.home .lede { font-size: 19px; color: var(--muted); max-width: 640px; }
.home .loop {
  display: inline-block; margin: 8px 0 28px; padding: 10px 16px; border-radius: 10px;
  background: var(--accent-soft); color: var(--accent); font-weight: 600;
  font: 600 14px ui-monospace, monospace;
}
.home .cards { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 8px 0 16px; }
.home .card {
  display: block; padding: 18px 20px; border: 1px solid var(--border); border-radius: 12px;
  color: var(--text); background: var(--bg);
}
.home .card:hover { border-color: var(--accent); text-decoration: none; transform: translateY(-1px); transition: .15s; }
.home .card h3 { margin: 0 0 6px; color: var(--accent); }
.home .card p { margin: 0; color: var(--muted); font-size: 14.5px; }
.home .muted { color: var(--muted); }

/* Mobile */
@media (max-width: 860px) {
  .topbar #menu { display: block; order: -1; }
  .topbar #filter { width: 140px; }
  .sidebar {
    position: fixed; left: 0; top: var(--topbar-h); z-index: 15;
    background: var(--bg); transform: translateX(-100%); transition: transform .2s;
    box-shadow: 2px 0 20px rgba(0,0,0,.15);
  }
  .sidebar.open { transform: translateX(0); }
  .content { padding: 28px 20px 80px; }
}