:root{
  --ink:#1c2434; --ink-2:#4a5568; --ink-3:#77839a;
  --line:#e4e9f2; --line-2:#eef2f8;
  --paper:#ffffff; --bg:#f5f7fb; --soft:#f8fafd;
  --brand:#3a63d8; --brand-soft:#eaf0ff;
  --radius:14px; --maxw:860px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0; background:var(--bg); color:var(--ink);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei","Hiragino Sans GB",sans-serif;
  font-size:15px; line-height:1.85; -webkit-font-smoothing:antialiased;
}
a{color:var(--brand); text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:var(--maxw); margin:0 auto; padding:0 20px 64px}

/* 顶部 */
.top{display:flex; align-items:center; justify-content:space-between; gap:16px; flex-wrap:wrap; padding:28px 0 22px}
.brand{display:flex; align-items:center; gap:10px; font-weight:700; font-size:16px; color:var(--ink)}
.brand:hover{text-decoration:none}
.brand .mark{
  width:30px; height:30px; border-radius:9px; flex:0 0 30px;
  background:linear-gradient(135deg,#5b7ff0,#8a6ce8);
  display:grid; place-items:center; color:#fff; font-size:14px; font-weight:800;
  box-shadow:0 4px 12px rgba(91,127,240,.28);
}
.brand small{display:block; font-size:11px; font-weight:500; color:var(--ink-3); line-height:1.2}
.nav{display:flex; gap:6px; flex-wrap:wrap}
.nav a{
  padding:7px 13px; border-radius:999px; font-size:13px; color:var(--ink-2);
  border:1px solid transparent;
}
.nav a:hover{background:#fff; border-color:var(--line); text-decoration:none}
.nav a.on{background:var(--brand-soft); color:var(--brand); font-weight:600; border-color:#d6e0ff}

/* 文档纸面 */
.paper{
  background:var(--paper); border:1px solid var(--line); border-radius:var(--radius);
  box-shadow:0 6px 28px rgba(28,36,52,.06); padding:44px 48px 40px;
}
.paper-hd{padding-bottom:26px; border-bottom:1px solid var(--line)}
.eyebrow{font-size:12px; letter-spacing:.08em; color:var(--brand); font-weight:600; margin-bottom:10px}
h1{margin:0 0 12px; font-size:30px; line-height:1.35; letter-spacing:-.01em}
.meta{font-size:12.5px; color:var(--ink-3); display:flex; gap:8px; flex-wrap:wrap; margin-bottom:20px}
.meta span{background:var(--soft); border:1px solid var(--line-2); padding:3px 10px; border-radius:999px}
.intro{margin:0; font-size:14.5px; color:var(--ink-2); line-height:1.9}
strong{color:var(--ink); font-weight:700}

/* 目录 */
.toc{
  margin:26px 0 32px; padding:18px 22px; border-radius:10px;
  background:var(--soft); border:1px solid var(--line-2);
}
.toc b{display:block; font-size:12.5px; color:var(--ink-3); letter-spacing:.06em; margin-bottom:10px}
.toc ul{margin:0; padding-left:0; list-style:none; columns:2; column-gap:32px; font-size:13.5px}
.toc li{margin:3px 0; break-inside:avoid}
.toc a{color:var(--ink-2)}

/* 正文 */
article section{margin:0 0 34px; scroll-margin-top:24px}
article h2{
  margin:0 0 14px; font-size:18px; line-height:1.5; color:var(--ink);
  padding-left:13px; border-left:3px solid var(--brand);
}
article p{margin:0 0 12px; color:var(--ink-2)}
article ul{margin:0; padding-left:22px}
article li{margin:8px 0; color:var(--ink-2); padding-left:4px}
article li::marker{color:var(--brand)}
.paper-ft{
  margin-top:36px; padding-top:20px; border-top:1px solid var(--line);
  font-size:12.5px; color:var(--ink-3);
}

/* 页脚 */
.foot{
  display:flex; justify-content:space-between; gap:14px; flex-wrap:wrap;
  margin-top:22px; font-size:12.5px; color:var(--ink-3);
}
.foot a{margin-right:14px}

/* 索引页卡片 */
.hero{padding:8px 0 26px}
.hero h1{font-size:28px}
.hero p{color:var(--ink-2); margin:0; max-width:640px}
.cards{display:grid; grid-template-columns:repeat(auto-fit,minmax(230px,1fr)); gap:14px; margin-top:8px}
.card{
  display:block; padding:22px; border-radius:12px; background:#fff;
  border:1px solid var(--line); transition:border-color .15s, transform .15s, box-shadow .15s;
}
.card:hover{
  text-decoration:none; border-color:#c8d6ff; transform:translateY(-2px);
  box-shadow:0 8px 24px rgba(58,99,216,.10);
}
.card .no{font-size:11px; letter-spacing:.1em; color:var(--brand); font-weight:700}
.card h3{margin:8px 0 8px; font-size:18px; color:var(--ink)}
.card p{margin:0 0 14px; font-size:13px; color:var(--ink-3); line-height:1.7}
.card .go{font-size:13px; font-weight:600; color:var(--brand)}
.note{
  margin-top:24px; padding:16px 20px; border-radius:10px;
  background:var(--brand-soft); border:1px solid #dce5ff;
  font-size:13px; color:var(--ink-2); line-height:1.8;
}

@media (max-width:640px){
  .paper{padding:28px 22px}
  h1{font-size:24px}
  .toc ul{columns:1}
  .top{padding:20px 0 16px}
}
@media print{
  body{background:#fff}
  .top nav,.foot,.toc{display:none}
  .paper{border:0; box-shadow:none; padding:0}
  article section{break-inside:avoid}
}