:root {
    --bg: #ffffff;
    --text: #1f2937;
    --muted: #6b7280;
    --rule: #e5e7eb;
    --accent: #1d4ed8;
    --note-bg: #f3f6fb;
  }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
      --bg: #0f172a;
      --text: #e5e7eb;
      --muted: #9ca3af;
      --rule: #273244;
      --accent: #7aa2ff;
      --note-bg: #16213a;
    }
  }
  :root[data-theme="dark"] {
    --bg: #0f172a;
    --text: #e5e7eb;
    --muted: #9ca3af;
    --rule: #273244;
    --accent: #7aa2ff;
    --note-bg: #16213a;
  }
  * { box-sizing: border-box; }
  body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font: 16px/1.75 -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
  }
  main { max-width: 760px; margin: 0 auto; padding: 32px 16px 64px; }
  header { border-bottom: 1px solid var(--rule); padding-bottom: 16px; margin-bottom: 8px; }
  .brand { color: var(--muted); font-size: 14px; text-decoration: none; }
  .langs { float: right; font-size: 14px; }
  .langs a { color: var(--accent); text-decoration: none; margin-left: 12px; }
  h1 { font-size: 28px; line-height: 1.3; margin: 20px 0 4px; }
  h2 { font-size: 19px; margin: 32px 0 8px; }
  .meta { color: var(--muted); font-size: 14px; margin: 0; }
  p, li { overflow-wrap: anywhere; }
  ul { padding-left: 22px; }
  li { margin: 4px 0; }
  a { color: var(--accent); }
  .note { background: var(--note-bg); border-radius: 8px; padding: 12px 16px; }
  section.lang + section.lang { border-top: 2px solid var(--rule); margin-top: 56px; padding-top: 8px; }
  code { font-size: 14px; }