:root{
    --ink:#0a2540; --ink-2:#425466; --ink-3:#8792a2;
    --brand:#635bff; --brand-soft:#f0f0ff;
    --line:#e3e8ee; --line-2:#eef2f7; --bg:#f6f9fc; --card:#ffffff;
    --warn-bg:#fff8e6; --warn-br:#f0b429; --warn-ink:#7a5b00;
    --info-bg:#eaf4ff; --info-br:#3d8bfd; --info-ink:#0b4ea2;
    --ok-bg:#e8f8ee; --ok-br:#12b76a;
    --del:#c0392b; --code-bg:#f2f4f7; --code-ink:#c2255c;
  }
  *{margin:0;padding:0;box-sizing:border-box}
  html{scroll-behavior:smooth}
  body{
    font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",Arial,sans-serif;
    line-height:1.75;color:var(--ink-2);background:var(--bg);
    -webkit-font-smoothing:antialiased;
  }
  .wrap{max-width:1180px;margin:0 auto;padding:0 24px 96px}

  /* ── Header ── */
  header.hero{
    background:linear-gradient(120deg,#0a2540 0%,#1b3a63 45%,#3b2f7a 100%);
    color:#fff;padding:56px 0 52px;margin-bottom:36px;
    border-bottom:4px solid var(--brand);
  }
  header.hero .wrap{padding-bottom:0}
  .eyebrow{font-size:12px;letter-spacing:.16em;text-transform:uppercase;opacity:.72;font-weight:600;margin-bottom:10px}
  header.hero h1{font-size:32px;line-height:1.3;font-weight:700;color:#fff;letter-spacing:-.01em}
  .meta{margin-top:22px;display:flex;flex-wrap:wrap;gap:8px 10px}
  .chip{
    background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.22);
    border-radius:999px;padding:5px 13px;font-size:12.5px;color:#e9eef5;
  }
  .chip b{color:#fff;font-weight:600}

  /* ── Sections ── */
  section.chapter{
    background:var(--card);border:1px solid var(--line);border-radius:12px;
    padding:30px 34px;margin:0 0 26px;
    box-shadow:0 1px 2px rgba(16,24,40,.05);
  }
  h2{
    font-size:21px;color:var(--ink);font-weight:700;letter-spacing:-.01em;
    padding-bottom:12px;border-bottom:2px solid var(--line-2);margin-bottom:22px;
    display:flex;align-items:baseline;gap:11px;
  }
  h2 .num{
    background:var(--brand);color:#fff;font-size:13px;font-weight:700;
    border-radius:6px;padding:3px 9px;flex:none;letter-spacing:.02em;
  }
  h3{font-size:16px;color:var(--ink);font-weight:650;margin:26px 0 12px;padding-left:11px;border-left:3px solid var(--brand)}
  h4{font-size:14.5px;color:var(--ink);font-weight:650;margin:18px 0 8px}
  p{margin:10px 0}
  ul,ol{margin:10px 0 10px 22px}
  li{margin:5px 0}
  strong{color:var(--ink);font-weight:650}

  /* ── Tables ── */
  .tw{overflow-x:auto;margin:18px 0;border:1px solid var(--line);border-radius:9px}
  table{width:100%;border-collapse:collapse;font-size:13.5px;background:#fff}
  thead th{
    background:#f4f6fa;color:var(--ink);font-weight:650;text-align:left;
    padding:11px 13px;border-bottom:1px solid var(--line);white-space:nowrap;
  }
  tbody td{padding:10px 13px;border-bottom:1px solid var(--line-2);vertical-align:top}
  tbody tr:last-child td{border-bottom:none}
  tbody tr:nth-child(even){background:#fafbfd}
  tbody tr:hover{background:var(--brand-soft)}
  td.c,th.c{text-align:center;white-space:nowrap}
  td code{white-space:nowrap}

  /* ── Inline ── */
  code{
    background:var(--code-bg);color:var(--code-ink);padding:1.5px 6px;
    border-radius:5px;font-family:"SF Mono",Menlo,Consolas,monospace;font-size:.875em;
    border:1px solid #e6e9ef;
  }
  .api{
    display:inline-block;background:#0a2540;color:#7ee2b8;padding:2px 9px;border-radius:5px;
    font-family:"SF Mono",Menlo,Consolas,monospace;font-size:13px;font-weight:600;
  }
  .m{font-family:"SF Mono",Menlo,Consolas,monospace;font-size:13px;font-weight:650;color:var(--ink);white-space:nowrap}
  s{color:var(--del);text-decoration-thickness:1.5px}

  /* ── Callouts ── */
  .note{
    margin:16px 0;padding:14px 18px;border-radius:8px;
    background:var(--info-bg);border-left:4px solid var(--info-br);font-size:13.5px;color:var(--info-ink);
  }
  .note.warn{background:var(--warn-bg);border-color:var(--warn-br);color:var(--warn-ink)}
  .note.ok{background:var(--ok-bg);border-color:var(--ok-br);color:#0a5c37}
  .note .tag{
    display:inline-block;font-size:11px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;
    margin-right:8px;opacity:.8;
  }
  .note ul{margin:6px 0 4px 20px}
  .note p{margin:5px 0}
  .note p+p{margin-top:9px}

  /* ── Badges ── */
  .b{
    display:inline-block;padding:1px 8px;border-radius:5px;font-size:11.5px;font-weight:650;
    white-space:nowrap;line-height:1.6;
  }
  .b-new{background:#e8f8ee;color:#087443;border:1px solid #a7e3c2}
  .b-old{background:#fdecec;color:#a52620;border:1px solid #f3c0bd}
  .b-req{background:#fdecec;color:#a52620;border:1px solid #f3c0bd}
  .b-opt{background:#fff4e5;color:#92400e;border:1px solid #f5d9a8}
  .b-keep{background:#eaf4ff;color:#0b4ea2;border:1px solid #bcd9fb}
  .b-cu{background:#fdecec;color:#a52620;border:1px solid #f3c0bd}
  .b-note{background:#fff8e6;color:#7a5b00;border:1px solid #f0d79b}

  /* ── Matrix marks ── */
  .y{color:#087443;font-weight:700}
  .n{color:#b6bcc7;font-weight:600}
  .u{color:#92400e;font-weight:650;font-size:12.5px}

  /* ── TOC ── */
  nav.toc{
    background:var(--card);border:1px solid var(--line);border-radius:12px;
    padding:22px 28px;margin-bottom:26px;box-shadow:0 1px 2px rgba(16,24,40,.05);
  }
  nav.toc h2{font-size:13px;letter-spacing:.12em;text-transform:uppercase;color:var(--ink-3);border:none;margin-bottom:12px;padding:0}
  nav.toc ol{list-style:none;margin:0;counter-reset:t}
  nav.toc li{counter-increment:t;margin:0}
  nav.toc li a{
    display:flex;gap:10px;padding:7px 8px;border-radius:6px;text-decoration:none;color:var(--ink-2);font-size:14px;
  }
  nav.toc li a:hover{background:var(--brand-soft);color:var(--brand)}
  nav.toc li a::before{
    content:counter(t,decimal-leading-zero);font-family:"SF Mono",Menlo,monospace;
    font-size:11.5px;color:var(--ink-3);flex:none;padding-top:2px;font-weight:600;
  }
  nav.toc li a span{color:var(--ink-3);font-size:12.5px;margin-left:auto;font-family:"SF Mono",Menlo,monospace}

  footer{
    margin-top:40px;padding-top:20px;border-top:1px solid var(--line);
    font-size:12.5px;color:var(--ink-3);display:flex;justify-content:space-between;flex-wrap:wrap;gap:8px;
  }
  @media (max-width:720px){
    header.hero h1{font-size:24px}
    section.chapter{padding:22px 18px}
    .wrap{padding:0 14px 60px}
  }