:root{
  --brand:#1f6fd6; --brand-d:#1657ad; --brand-l:#eaf2fe;
  --ink:#1f2733; --sub:#5b6675; --line:#eef1f5; --bg:#eef1f6;
  --ok:#12a150; --ok-bg:#e9f8ef; --warn:#e8590c; --warn-bg:#fff2e8;
  --danger:#d6336c; --danger-bg:#ffeef4; --info:#1f6fd6; --info-bg:#eaf2fe;
  --card:#ffffff; --radius:16px; --shadow:0 4px 18px rgba(24,49,83,.07);
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent;}
body{margin:0;background:var(--bg);color:var(--ink);
  font:16px/1.8 -apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Segoe UI",sans-serif;
  -webkit-font-smoothing:antialiased;}
img{max-width:100%;}

/* 顶部栏 */
.topbar{position:sticky;top:0;z-index:20;
  background:linear-gradient(120deg,var(--brand),var(--brand-d));
  color:#fff;display:flex;align-items:center;gap:10px;
  padding:13px 16px;box-shadow:0 2px 12px rgba(22,87,173,.28);}
.topbar .back{color:#fff;text-decoration:none;font-size:20px;line-height:1;
  width:30px;height:30px;display:flex;align-items:center;justify-content:center;
  border-radius:50%;background:rgba(255,255,255,.16);flex:0 0 auto;}
.topbar h1{font-size:17px;margin:0;font-weight:600;flex:1;text-align:center;
  padding-right:40px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;}

/* 页头 hero */
.hero{background:linear-gradient(135deg,var(--brand),var(--brand-d));
  color:#fff;padding:22px 18px 30px;position:relative;overflow:hidden;}
.hero::after{content:"";position:absolute;right:-40px;top:-40px;
  width:150px;height:150px;border-radius:50%;background:rgba(255,255,255,.10);}
.hero::before{content:"";position:absolute;right:30px;bottom:-30px;
  width:90px;height:90px;border-radius:50%;background:rgba(255,255,255,.08);}
.hero .eyebrow{font-size:12.5px;opacity:.9;letter-spacing:2px;margin:0 0 6px;color:rgba(255,255,255,.88);}
.hero .htitle{font-size:24px;font-weight:700;margin:0;position:relative;z-index:1;}
.hero .hdesc{font-size:13px;opacity:.92;margin:8px 0 0;position:relative;z-index:1;color:rgba(255,255,255,.88);}

.wrap{max-width:860px;margin:-16px auto 0;padding:0 14px 40px;position:relative;z-index:2;}

/* 目录 TOC */
.toc{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
  padding:14px 16px;margin:0 0 16px;}
.toc .toc-h{font-size:13px;color:var(--sub);font-weight:600;margin:0 0 10px;
  display:flex;align-items:center;gap:6px;}
.toc .toc-h::before{content:"";width:4px;height:14px;background:var(--brand);border-radius:2px;}
.toc ol{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:8px;}
.toc li{margin:0;min-width:0;max-width:100%;}
.toc a{display:inline-flex;align-items:center;gap:6px;text-decoration:none;
  background:var(--brand-l);color:var(--brand-d);font-size:13px;font-weight:500;
  padding:7px 12px;border-radius:20px;max-width:100%;white-space:normal;line-height:1.4;}
.toc a .n{display:inline-flex;align-items:center;justify-content:center;
  width:18px;height:18px;border-radius:50%;background:var(--brand);color:#fff;font-size:11px;flex:0 0 18px;}

/* 区块卡片 */
.sec{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
  padding:6px 16px 16px;margin:0 0 16px;scroll-margin-top:64px;}
.sec-head{display:flex;align-items:center;gap:10px;padding:14px 0 6px;
  border-bottom:1px solid var(--line);margin-bottom:12px;}
.sec-head .ico{flex:0 0 auto;width:34px;height:34px;border-radius:10px;
  background:var(--brand-l);color:var(--brand);display:flex;align-items:center;
  justify-content:center;font-size:18px;}
.sec-head h2{font-size:18px;margin:0;color:var(--ink);font-weight:700;}

h3{font-size:15.5px;margin:16px 0 8px;color:var(--brand-d);font-weight:600;
  padding-left:10px;border-left:3px solid var(--brand);}
h4{font-size:15px;margin:14px 0 6px;color:var(--ink);font-weight:600;}
p{margin:9px 0;color:#2d3643;}
strong{color:var(--danger);font-weight:600;}
a{color:var(--brand);word-break:break-all;}

/* 普通列表 */
ul,ol{margin:9px 0;padding-left:4px;list-style:none;}
ul>li,ol>li{position:relative;padding-left:22px;margin:7px 0;color:#2d3643;}
ul>li::before{content:"";position:absolute;left:6px;top:11px;width:6px;height:6px;
  border-radius:50%;background:var(--brand);}
ol{counter-reset:li;}
ol>li{counter-increment:li;}
ol>li::before{content:counter(li);position:absolute;left:0;top:2px;
  width:19px;height:19px;border-radius:50%;background:var(--brand);color:#fff;
  font-size:11.5px;font-weight:600;display:flex;align-items:center;justify-content:center;line-height:1;}
.toc ol>li::before{display:none;}
li ul,li ol{margin:6px 0;}

/* 提示框 callout */
.callout{border-radius:12px;padding:12px 14px 12px 14px;margin:12px 0;
  font-size:14px;line-height:1.75;position:relative;padding-left:42px;}
.callout .ci{position:absolute;left:13px;top:12px;font-size:17px;}
.callout p{margin:4px 0;color:inherit;}
.callout.info{background:var(--info-bg);color:#194b8f;}
.callout.tip{background:var(--ok-bg);color:#0d6b38;}
.callout.warn{background:var(--warn-bg);color:#9a4111;}
.callout.danger{background:var(--danger-bg);color:#a3134d;}
.callout .ctitle{font-weight:700;margin-right:4px;}

/* 高亮数据条 */
.stat{display:flex;flex-wrap:wrap;gap:10px;margin:12px 0;}
.stat .item{flex:1 1 40%;min-width:120px;background:var(--brand-l);
  border-radius:12px;padding:12px 14px;}
.stat .item .v{font-size:19px;font-weight:700;color:var(--brand-d);line-height:1.3;}
.stat .item .k{font-size:12.5px;color:var(--sub);margin-top:2px;}

/* 问答块 */
.qa{background:linear-gradient(180deg,#fbfcff,#fff);
  border:1px solid var(--brand-l);border-radius:12px;padding:12px 14px;margin:14px 0;}
.qa .q{font-weight:700;color:var(--brand-d);font-size:15px;
  display:flex;gap:8px;align-items:flex-start;}
.qa .q .badge{flex:0 0 auto;background:var(--brand);color:#fff;border-radius:6px;
  font-size:12px;padding:1px 7px;line-height:1.6;}

/* 图片 */
.imgwrap{text-align:center;margin:14px 0;}
.imgwrap img{border-radius:12px;box-shadow:var(--shadow);}

/* 页脚 */
.foot{text-align:center;color:#9aa4b2;font-size:12px;padding:10px 0 30px;}
.foot .home{display:inline-block;margin-top:8px;color:var(--brand);
  text-decoration:none;font-weight:600;background:var(--brand-l);
  padding:8px 20px;border-radius:20px;}

/* 电信专栏强调（menu_04） */
.telecom .hero{background:linear-gradient(135deg,#0a7bd8,#0555a6);}
.telecom .badge-op{display:inline-block;background:rgba(255,255,255,.18);
  border:1px solid rgba(255,255,255,.4);border-radius:20px;padding:3px 12px;
  font-size:12px;margin-top:10px;position:relative;z-index:1;}

@media(max-width:480px){
  .toc ol{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));}
  .toc a{width:100%;height:100%;overflow-wrap:anywhere;}
  .hero .htitle{font-size:22px;}
}