:root {
  --ink: #111827;
  --muted: #6b7280;
  --line: #e5e7eb;
  --brand: #0f766e;
  --bg: #f8fafc;
  --panel: #fff;
  --font: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
}
* { box-sizing: border-box; }
html, body { margin: 0; min-height: 100%; background: var(--bg); color: var(--ink); font: 16px/1.6 var(--font); }
.top {
  display: flex; gap: 16px; align-items: center; padding: 12px 20px;
  background: var(--panel); border-bottom: 1px solid var(--line); position: sticky; top: 0;
}
.brand { display: flex; gap: 8px; align-items: center; color: var(--ink); text-decoration: none; font-weight: 600; }
#helpQ { flex: 1; max-width: 360px; border: 1px solid var(--line); border-radius: 8px; padding: 8px 12px; }
main { display: grid; grid-template-columns: 280px 1fr; min-height: calc(100vh - 58px); }
.list { border-right: 1px solid var(--line); background: var(--panel); overflow: auto; padding: 12px; }
.list a {
  display: block; padding: 10px 12px; border-radius: 8px; color: var(--ink); text-decoration: none; margin-bottom: 4px;
}
.list a:hover, .list a.is-on { background: #ecfdf5; color: var(--brand); }
.list .cat { font-size: 12px; color: var(--muted); text-transform: none; padding: 8px 12px; }
.article { padding: 28px 36px; max-width: 760px; }
.article h1, .article h2, .article h3 { line-height: 1.3; }
.muted { color: var(--muted); }
@media (max-width: 800px) {
  main { grid-template-columns: 1fr; }
  .list { border-right: 0; border-bottom: 1px solid var(--line); max-height: 40vh; }
  .article { padding: 20px; }
}