:root{
  --bg:#f2f5f9;
  --surface:#ffffff;
  --surface-soft:#f7f9fc;
  --text:#142033;
  --muted:#5c6b82;
  --brand:#0c5df4;
  --brand-deep:#0a3d9a;
  --accent:#f59f0b;
  --border:#dbe3ef;
  --radius:18px;
  --max:1120px;
  --shadow:0 18px 40px rgba(13, 39, 80, 0.08);
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family:"Avenir Next","SF Pro Text","Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  color:var(--text);
  background:
    radial-gradient(900px 520px at 8% -12%, rgba(12,93,244,.16), transparent 58%),
    radial-gradient(900px 560px at 92% -15%, rgba(245,159,11,.12), transparent 60%),
    var(--bg);
}
a{color:inherit}
.wrap{max-width:var(--max);margin:0 auto;padding:0 20px}
.skip-link{
  position:absolute;left:-999px;top:auto;width:1px;height:1px;overflow:hidden;
}
.skip-link:focus{
  left:20px;top:20px;width:auto;height:auto;overflow:visible;
  background:#fff;border:1px solid var(--border);padding:10px 12px;border-radius:12px;
}

.nav{
  position:sticky;top:0;z-index:10;
  backdrop-filter:blur(10px);
  background:rgba(242,245,249,.88);
  border-bottom:1px solid var(--border);
}
.nav-inner{
  display:flex;align-items:center;justify-content:space-between;
  padding:14px 0;
  gap:18px;
}
.brand{
  display:flex;align-items:center;gap:10px;
  font-weight:800;letter-spacing:.1px;text-decoration:none;
}
.logo{
  width:36px;height:36px;border-radius:11px;
  background:linear-gradient(140deg,var(--brand),var(--brand-deep));
  color:#fff;
  display:grid;place-items:center;
  box-shadow:0 8px 18px rgba(12,93,244,.22);
}
.logo span{font-weight:900}
.nav-links{
  display:flex;flex-wrap:wrap;gap:14px;justify-content:flex-end;
}
.nav a{color:var(--muted);text-decoration:none;font-weight:650}
.nav a:hover,.nav a:focus-visible{color:var(--brand-deep);text-decoration:underline}

main{padding:36px 0 14px}
.hero{
  padding:54px 0 44px;
  text-align:center;
}
.hero h1{
  font-size:clamp(34px,5vw,56px);
  line-height:1.08;
  margin:0 0 16px;
  color:#0f2348;
}
.hero p{
  color:var(--muted);
  max-width:780px;
  margin:0 auto 24px;
  font-size:18px;
  line-height:1.75;
}
.cta{display:inline-flex;gap:12px;flex-wrap:wrap;justify-content:center}
.btn{
  padding:12px 18px;border-radius:14px;
  font-weight:800;text-decoration:none;
  background:#fff;
  border:1px solid var(--border);
  display:inline-flex;align-items:center;gap:10px;
}
.btn.primary{
  background:linear-gradient(135deg,var(--brand),var(--brand-deep));
  color:#fff;
  border-color:transparent;
  box-shadow:0 10px 22px rgba(12,93,244,.26);
}
.section{padding:48px 0}
.section h2{font-size:30px;margin:0 0 22px;text-align:center}
.grid{
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(240px,1fr));
  gap:18px;
}
.card{
  background:var(--surface);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:22px;
  box-shadow:var(--shadow);
}
.card h3{margin:0 0 8px;color:#15335f}
.card p{margin:0;color:var(--muted);line-height:1.65}
.badge{
  display:inline-flex;align-items:center;gap:8px;
  background:rgba(12,93,244,.10);
  border:1px solid rgba(12,93,244,.24);
  color:var(--brand-deep);
  padding:7px 11px;border-radius:999px;
  font-weight:800;font-size:13px;
}
.note{
  max-width:860px;margin:0 auto;
  background:var(--surface);
  border:1px solid var(--border);
  border-left:5px solid var(--accent);
  border-radius:var(--radius);
  padding:18px;
  color:#30455f;
  line-height:1.75;
  box-shadow:var(--shadow);
}
.note ul{margin:0;padding-left:20px}
.page-title{
  margin:0 auto 8px;
  max-width:860px;
  font-size:36px;
  color:#132f58;
}
.page-sub{
  margin:0 auto 18px;
  color:var(--muted);
  max-width:860px;
  line-height:1.75;
}
.prose{
  max-width:860px;margin:0 auto;
  background:var(--surface);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:24px;
  line-height:1.85;
  color:#263a52;
  box-shadow:var(--shadow);
}
.prose h2{margin:18px 0 10px;font-size:21px;color:#15335f}
.prose ul{margin:10px 0 0 18px}
.prose code{
  background:rgba(12,93,244,.08);
  color:#0d4ccc;
  padding:2px 6px;
  border-radius:8px;
}
.kv{
  display:grid;
  grid-template-columns:170px 1fr;
  gap:10px 14px;
  margin:10px 0 0;
}
.kv div{
  padding:9px 10px;
  border:1px solid var(--border);
  border-radius:12px;
  background:var(--surface-soft);
}
.kv .k{color:#3f5878;font-weight:800}
footer{
  border-top:1px solid var(--border);
  padding:26px 0;
  color:var(--muted);
  font-size:14px;
  text-align:center;
}
.footer-links{
  display:flex;gap:14px;flex-wrap:wrap;justify-content:center;
  margin:8px 0 0;
}
.footer-links a{color:#506889;text-decoration:none;font-weight:700}
.footer-links a:hover,.footer-links a:focus-visible{color:var(--brand-deep);text-decoration:underline}
.small{font-size:12px;color:#6c7f98;margin-top:10px}
.lang-note{max-width:860px;margin:0 auto 14px;color:#586c87;font-size:14px;line-height:1.6}
hr.sep{border:0;border-top:1px solid var(--border);margin:18px 0}

@media (max-width:760px){
  .nav-inner{align-items:flex-start;flex-direction:column}
  .hero{padding-top:36px}
  .hero p{font-size:16px}
  .section h2{font-size:26px}
  .page-title{font-size:30px}
  .kv{grid-template-columns:1fr}
}