:root{
  --bg:#f2f6f9;
  --card:#ffffff;
  --ink:#142a36;
  --muted:#67808d;
  --line:rgba(23,58,78,.10);
  --blue:#007aff;
  --blue-deep:#005fc7;
  --orange:#f59a3c;
  --copper:#c77a43;
  --green:#18a874;
  --shadow:0 18px 50px rgba(25,60,82,.09);
  --font-ui:-apple-system,BlinkMacSystemFont,"SF Pro Text","Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --font-cn:"PingFang SC","Microsoft YaHei","Noto Sans SC",sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;background:
    radial-gradient(900px 520px at 8% -10%, rgba(0,122,255,.10), transparent 65%),
    radial-gradient(720px 440px at 100% 0%, rgba(245,154,60,.08), transparent 62%),
    var(--bg);
  color:var(--ink);font-family:var(--font-ui);line-height:1.7;-webkit-font-smoothing:antialiased;
}
a{color:var(--blue);text-decoration:none}
a:hover{text-decoration:none}
.topbar{
  position:sticky;top:0;z-index:50;display:flex;align-items:center;justify-content:space-between;gap:16px;
  padding:12px 22px;background:rgba(242,246,249,.86);border-bottom:1px solid rgba(20,60,80,.08);
  backdrop-filter:blur(18px)
}
.brand{display:flex;align-items:center;gap:10px;min-width:0}
.brand-mark{
  width:30px;height:36px;border-radius:9px;background:linear-gradient(145deg,#162b3a,#07121b);
  display:grid;place-items:center;color:#fff;box-shadow:0 6px 16px rgba(13,42,62,.18);flex:0 0 auto
}
.brand-mark svg{width:19px;height:24px}
.brand-copy{display:flex;flex-direction:column;line-height:1.15}
.brand-copy b{font-family:var(--font-cn);font-size:14px;letter-spacing:.08em}
.brand-copy small{font-size:7px;color:var(--muted);letter-spacing:.15em;font-weight:700;margin-top:3px}
.top-actions{display:flex;align-items:center;gap:8px;flex:0 0 auto}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:7px;height:38px;padding:0 15px;border-radius:10px;
  border:1px solid rgba(20,60,80,.13);background:#fff;color:#31586b;
  font-family:var(--font-cn);font-size:11.5px;font-weight:700;cursor:pointer;white-space:nowrap
}
.btn:hover{background:#f8fbfd}
.btn--primary{background:var(--blue);border-color:var(--blue);color:#fff;box-shadow:0 8px 20px rgba(0,122,255,.18)}
.btn--primary:hover{background:var(--blue-deep)}
.btn--ghost{background:rgba(255,255,255,.7);color:#547082}
.wrap{max-width:1080px;margin:0 auto;padding:34px 22px 64px}
.hero{padding:22px 0 30px;border-bottom:1px solid var(--line)}
.eyebrow{display:flex;align-items:center;gap:8px;font:800 9px/1 var(--font-ui);letter-spacing:.16em;color:#78909f;margin-bottom:14px}
.eyebrow i{display:block;width:18px;height:1px;background:#9cb2be}
.hero h1{font-family:var(--font-cn);font-size:clamp(30px,4.5vw,50px);line-height:1.15;letter-spacing:-.02em;margin:0 0 10px;font-weight:700}
.hero h1 span{color:var(--blue)}
.hero .sub{font-family:var(--font-cn);font-size:clamp(15px,1.8vw,20px);color:#355a6f;margin:0 0 14px;font-weight:500}
.hero p{font-family:var(--font-cn);font-size:14px;color:var(--muted);max-width:780px;margin:0;line-height:1.85}
.hero-meta{display:flex;flex-wrap:wrap;gap:14px;margin-top:17px;font-family:var(--font-cn);font-size:11px;color:#6f8895}
.hero-meta b{color:#2e566b}
.hero-meta span{display:inline-flex;align-items:center;gap:5px}
.dot{width:5px;height:5px;border-radius:50%;background:var(--green);display:inline-block}
.module-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-top:22px}
.module{
  display:flex;flex-direction:column;min-height:230px;padding:20px;border:1px solid var(--line);border-radius:20px;
  background:var(--card);box-shadow:var(--shadow);color:inherit;transition:transform .22s ease,box-shadow .22s ease
}
.module:hover{transform:translateY(-3px);box-shadow:0 24px 58px rgba(25,60,82,.13)}
.module-top{display:flex;align-items:flex-start;justify-content:space-between;gap:12px}
.module-num{font:800 10px/1 var(--font-ui);letter-spacing:.08em;color:#8ca1ad}
.module-icon{
  width:40px;height:40px;border-radius:12px;display:grid;place-items:center;
  background:rgba(0,122,255,.08);color:var(--blue);font:800 15px/1 var(--font-ui)
}
.module--teardown .module-icon{background:rgba(199,122,67,.11);color:var(--copper)}
.module h2{font-family:var(--font-cn);font-size:26px;letter-spacing:-.01em;margin:12px 0 5px}
.module p{font-family:var(--font-cn);font-size:12.5px;color:var(--muted);margin:0;line-height:1.8}
.module-tags{display:flex;flex-wrap:wrap;gap:6px;margin-top:12px}
.module-tags span{padding:4px 8px;border-radius:6px;background:#f3f8fb;border:1px solid rgba(20,60,80,.07);font-family:var(--font-cn);font-size:9.5px;color:#63808f}
.module-foot{display:flex;align-items:center;justify-content:space-between;margin-top:auto;padding-top:17px}
.module-foot small{font-family:var(--font-cn);font-size:10px;color:#8a9da7}
.module-go{display:inline-flex;align-items:center;gap:6px;font-family:var(--font-cn);font-size:11px;font-weight:700;color:var(--blue)}
.module--teardown .module-go{color:var(--copper)}
.path{
  display:grid;grid-template-columns:1fr auto 1fr;gap:10px;align-items:center;
  margin-top:20px;padding:14px 16px;border:1px dashed rgba(20,60,80,.15);border-radius:14px;
  font-family:var(--font-cn);font-size:11px;color:#6a8492;background:rgba(255,255,255,.5)
}
.path b{color:#2f566a}
.path i{font-style:normal;color:#a0b2bb}
.note{margin-top:20px;padding:14px 16px;border-radius:14px;background:rgba(0,122,255,.055);border:1px solid rgba(0,122,255,.12);font-family:var(--font-cn);font-size:11.5px;color:#4f7080;line-height:1.8}
.note b{color:#245064}
.page-footer{margin-top:36px;padding-top:18px;border-top:1px solid var(--line);font-family:var(--font-cn);font-size:9.5px;color:#8ca1ab;line-height:1.8}
.page-footer b{color:#6b8390}
.tocline{display:flex;flex-wrap:wrap;gap:6px;margin-top:18px}
.tocline a{padding:6px 9px;border:1px solid var(--line);border-radius:7px;background:#fff;font-family:var(--font-cn);font-size:10px;color:#5d7b8b}
.tocline a:hover{border-color:rgba(0,122,255,.3);color:var(--blue-deep)}
/* teardown */
.step-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:11px;margin-top:22px}
.step-card{padding:15px;border:1px solid var(--line);border-radius:14px;background:#fff}
.step-card .num{font:800 9px/1 var(--font-ui);letter-spacing:.1em;color:var(--blue)}
.step-card h3{font-family:var(--font-cn);font-size:15px;margin:8px 0 3px}
.step-card p{font-family:var(--font-cn);font-size:10.5px;color:#748c98;margin:0;line-height:1.65}
.cta-band{
  display:flex;align-items:center;justify-content:space-between;gap:18px;flex-wrap:wrap;
  margin-top:24px;padding:20px;border-radius:18px;background:linear-gradient(135deg,#102b3d,#071620);color:#fff
}
.cta-band h2{font-family:var(--font-cn);font-size:22px;margin:0 0 4px}
.cta-band p{font-family:var(--font-cn);font-size:11px;color:#9fb7c4;margin:0}
.cta-band .btn{background:#fff;border-color:#fff;color:#102b3d}
.cta-band .btn:hover{background:#eaf8ff}
.tips{display:grid;grid-template-columns:1fr 1fr;gap:9px;margin-top:14px}
.tip{padding:11px 12px;border:1px solid var(--line);border-radius:10px;background:rgba(255,255,255,.65);font-family:var(--font-cn);font-size:10.5px;color:#657f8c}
.tip b{display:block;color:#2d5366;font-size:11px;margin-bottom:2px}
@media(max-width:760px){
  .topbar{padding:10px 13px}
  .brand-copy small{display:none}
  .brand-copy b{font-size:13px}
  .top-actions .btn--ghost{display:none}
  .wrap{padding:24px 15px 50px}
  .module-grid{grid-template-columns:1fr;gap:12px}
  .module{min-height:0;padding:17px}
  .module h2{font-size:23px}
  .step-grid{grid-template-columns:1fr 1fr;gap:8px}
  .path{grid-template-columns:1fr;gap:4px;text-align:center}
  .path i{transform:rotate(90deg)}
  .tips{grid-template-columns:1fr}
  .hero h1{font-size:31px}
}
@media(max-width:420px){
  .step-grid{grid-template-columns:1fr}
  .hero h1{font-size:28px}
}