:root{
      --bg:#ffffff;
      --text:#111827;
      --muted:#6b7280;
      --border:#e5e7eb;
      --card:#f9fafb;
      --brand:#0ea5e9;
    }
    *{box-sizing:border-box}
    body{
      margin:0;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, "Noto Sans", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      color:var(--text);
      background:var(--bg);
      line-height:1.6;
    }
    .wrap{
      max-width: 980px;
      margin: 0 auto;
      padding: 28px 18px 80px;
    }
    header{
      padding: 18px 18px 14px;
      border:1px solid var(--border);
      background: linear-gradient(180deg, #ffffff, #fbfdff);
      border-radius: 16px;
    }
    h1{
      margin:0 0 8px;
      font-size: 26px;
      letter-spacing: .2px;
    }
    .sub{
      margin:0;
      color:var(--muted);
      font-size: 14px;
    }
    .langbar{
      margin-top: 14px;
      display:flex;
      gap:10px;
      flex-wrap:wrap;
      align-items:center;
    }
    .pill{
      display:inline-flex;
      align-items:center;
      gap:8px;
      padding:8px 12px;
      border:1px solid var(--border);
      border-radius: 999px;
      background:#fff;
      text-decoration:none;
      color:var(--text);
      font-size:14px;
    }
    .pill:hover{border-color:#cbd5e1}
    .pill strong{color:var(--brand)}
    .note{
      margin-top:14px;
      padding:12px 14px;
      border:1px dashed var(--border);
      border-radius: 12px;
      background: var(--card);
      color: var(--muted);
      font-size: 13px;
    }
    section{
      margin-top: 18px;
      padding: 18px;
      border:1px solid var(--border);
      border-radius: 16px;
      background: #fff;
    }
    section h2{
      margin: 0 0 10px;
      font-size: 20px;
    }
    section h3{
      margin: 18px 0 8px;
      font-size: 16px;
    }
    ul{margin: 8px 0 0 20px}
    li{margin: 6px 0}
    .toc{
      margin-top: 16px;
      padding: 14px;
      border:1px solid var(--border);
      border-radius: 14px;
      background: var(--card);
    }
    .toc-title{
      margin:0 0 8px;
      font-weight:600;
    }
    .toc a{
      color: var(--brand);
      text-decoration:none;
    }
    .toc a:hover{text-decoration:underline}
    .grid{
      display:grid;
      grid-template-columns: 1fr;
      gap: 10px;
    }
    @media (min-width: 860px){
      .grid{grid-template-columns: 1fr 1fr}
    }
    .card{
      padding: 14px;
      border:1px solid var(--border);
      border-radius: 14px;
      background:#fff;
    }
    .muted{color:var(--muted)}
    .kbd{
      font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
      font-size: 12px;
      padding: 2px 6px;
      border:1px solid var(--border);
      border-radius: 8px;
      background:#fff;
    }
    footer{
      margin-top: 18px;
      color: var(--muted);
      font-size: 12px;
      text-align:center;
    }
    hr{
      border:0;
      border-top:1px solid var(--border);
      margin: 14px 0;
    }