:root{
  --navy:#0d2b45; --blue:#1565a5; --blue2:#1d7fc4;
  --gold:#e8a33d; --gray:#f5f7fa; --ink:#222; --mut:#5b6b7b;
  --line:#e2e8ef; --ok:#2e7d4f;
}
*{box-sizing:border-box;margin:0;padding:0}
body{font-family:"Segoe UI","Microsoft YaHei",Helvetica,Arial,sans-serif;color:var(--ink);line-height:1.65;background:#fff}
a{color:var(--blue);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:1180px;margin:0 auto;padding:0 22px}
.page{max-width:960px;margin:0 auto;padding:0 22px}
/* top bar */
.topbar{background:var(--navy);color:#cfe0f0;font-size:13px}
.topbar .wrap{display:flex;justify-content:space-between;align-items:center;height:38px;gap:14px;flex-wrap:wrap}
.topbar a{color:#cfe0f0}
.topbar .lang a{margin-left:14px;padding:2px 8px;border:1px solid #2c4a66;border-radius:3px}
/* nav */
header.nav{position:sticky;top:0;z-index:50;background:#fff;border-bottom:1px solid var(--line);box-shadow:0 2px 8px rgba(13,43,69,.06)}
header.nav .wrap{display:flex;align-items:center;justify-content:space-between;height:66px}
.logo{display:flex;align-items:baseline;gap:10px;font-weight:800;font-size:21px;color:var(--navy);letter-spacing:.5px}
.logo small{font-size:13px;color:var(--mut);font-weight:600}
nav.menu{display:flex;gap:22px;flex-wrap:wrap}
nav.menu a{color:var(--navy);font-weight:600;font-size:15px;padding:6px 0;border-bottom:2px solid transparent}
nav.menu a:hover{border-bottom-color:var(--gold);text-decoration:none}
nav.menu a.active{border-bottom-color:var(--gold)}
.nav-cta{background:var(--gold);color:#1a1a1a;padding:9px 18px;border-radius:5px;font-weight:700;font-size:14px}
.nav-cta:hover{text-decoration:none}
/* page hero (lighter than homepage) */
.phero{background:linear-gradient(120deg,var(--navy) 0%,#10395c 60%,var(--blue) 100%);color:#fff;padding:46px 0 40px}
.phero h1{font-size:32px;line-height:1.22;font-weight:800;margin-bottom:12px}
.phero h1 .hl{color:var(--gold)}
.phero p.lead{font-size:16px;color:#d7e6f4;max-width:720px}
.breadcrumb{font-size:13px;color:#bcd0e2;margin-bottom:14px}
.breadcrumb a{color:#bcd0e2}
.breadcrumb span{color:var(--gold)}
/* section */
section{padding:54px 0}
section h2{font-size:26px;color:var(--navy);margin-bottom:8px;font-weight:800}
section h3{font-size:19px;color:var(--navy);margin:26px 0 10px}
section .sub{color:var(--mut);margin-bottom:24px;font-size:15px}
.bar{width:54px;height:4px;background:var(--gold);margin-bottom:20px;border-radius:2px}
.alt{background:var(--gray)}
/* spec table */
table.spec{width:100%;border-collapse:collapse;background:#fff;font-size:14px;box-shadow:0 2px 10px rgba(13,43,69,.06);margin:14px 0 20px}
table.spec th{background:var(--navy);color:#fff;text-align:left;padding:11px 13px;font-weight:600;font-size:13px}
table.spec td{padding:10px 13px;border-bottom:1px solid var(--line);vertical-align:top}
table.spec tr:nth-child(even) td{background:#fafcfe}
table.spec code{background:#eef3fb;border:1px solid #cdddf2;border-radius:4px;padding:1px 6px;color:var(--blue);font-family:"Consolas",monospace;font-size:12.5px}
/* equivalent option cards */
.eqopts{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;margin:14px 0 22px}
.eqopt{background:#fff;border:1px solid var(--line);border-left:4px solid var(--blue);border-radius:9px;padding:18px;box-shadow:0 2px 10px rgba(13,43,69,.05)}
.eqopt h4{color:var(--navy);font-size:16px;margin-bottom:6px}
.eqopt .brand{font-size:12px;color:var(--mut);font-weight:700;letter-spacing:.5px;text-transform:uppercase}
.eqopt p{font-size:13.5px;color:var(--mut);margin:0}
.eqopt .pri{margin-top:8px;font-size:13px;color:var(--blue);font-weight:700}
/* materials */
.matlist{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin:10px 0 20px}
.mat{background:#fff;border:1px solid var(--line);border-radius:9px;padding:16px}
.mat b{color:var(--navy);display:block;font-size:15px;margin-bottom:4px}
.mat span{font-size:13px;color:var(--mut)}
/* faq */
.faq{margin:14px 0 22px}
.faq details{border:1px solid var(--line);border-radius:8px;padding:14px 16px;margin-bottom:10px;background:#fff}
.faq summary{font-weight:700;color:var(--navy);cursor:pointer;font-size:15px}
.faq details p{font-size:14px;color:var(--mut);margin-top:10px}
/* disclaimer (RED LINE) */
.disc{background:#fff8ec;border:1px solid #f3d9a6;border-left:4px solid var(--gold);border-radius:8px;padding:16px 18px;margin:22px 0;font-size:13.5px;color:#7a5a1e;line-height:1.7}
.disc b{color:#5b3f12}
/* cta band */
.cta{background:var(--navy);color:#fff;border-radius:12px;padding:28px 30px;margin:26px 0;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:16px}
.cta h3{color:#fff;font-size:20px;margin:0 0 6px}
.cta p{color:#cfe0f0;font-size:14px;margin:0}
.cta a{background:var(--gold);color:#1a1a1a;padding:12px 22px;border-radius:6px;font-weight:700;font-size:14px}
.cta a:hover{text-decoration:none}
/* related internal links (权重互导) */
.related{background:#eef6fc;border:1px solid #cfe2f2;border-radius:10px;padding:20px;margin:22px 0}
.related h4{color:var(--navy);font-size:15px;margin-bottom:12px}
.related ul{list-style:none;display:grid;grid-template-columns:1fr 1fr;gap:8px 22px}
.related li{font-size:14px;padding:4px 0;border-bottom:1px dashed #cfe2f2}
.related li a{color:var(--blue)}
/* hub grid */
.hubgrid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;margin:14px 0 22px}
.hubcard{background:#fff;border:1px solid var(--line);border-radius:10px;padding:20px;box-shadow:0 2px 10px rgba(13,43,69,.05);transition:border-color .15s}
.hubcard:hover{border-color:var(--blue)}
.hubcard .bk{font-size:12px;color:var(--mut);font-weight:700;letter-spacing:.5px;text-transform:uppercase}
.hubcard h4{color:var(--navy);font-size:18px;margin:4px 0 8px}
.hubcard p{font-size:13.5px;color:var(--mut);margin-bottom:12px}
.hubcard .more{font-weight:700;color:var(--blue);font-size:13.5px}
/* footer */
footer{background:var(--navy);color:#bcd0e2;padding:36px 0;font-size:13.5px;margin-top:30px}
footer .wrap{display:flex;justify-content:space-between;flex-wrap:wrap;gap:20px}
footer .col h5{color:#fff;font-size:15px;margin-bottom:10px}
footer .col a{color:#bcd0e2;display:block;padding:3px 0}
footer .bot{border-top:1px solid #23425e;margin-top:24px;padding-top:16px;color:#8aa6bf;font-size:12.5px}
footer .bot a{color:#8aa6bf}
@media(max-width:900px){
  nav.menu{display:none}
  .eqopts,.matlist,.hubgrid,.related ul{grid-template-columns:1fr}
  .cta{flex-direction:column;align-items:flex-start}
}