:root{--bg:#f6fafc;--white:#fff;--wash:#eaf6fa;--wash2:#edf4f8;--brand:#1787db;--cyan:#25c8d1;--sea:#174b78;--heading:#183a56;--body:#31485d;--muted:#687d8e;--line:#dce9f0;--footer:#123653;--max:1180px}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:135px}body{margin:0;background:var(--bg);color:var(--body);font:16px/1.8 Arial,"PingFang SC","Microsoft YaHei",sans-serif;overflow-x:hidden}a{color:var(--brand);text-underline-offset:4px}a:hover{color:#105b94}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--cyan);outline-offset:3px}img{max-width:100%;height:auto}h1,h2,h3{color:var(--heading);line-height:1.38;letter-spacing:-.025em}h1{font-size:clamp(27px,3.5vw,42px);margin:0 0 20px}h2{font-size:clamp(20px,2.25vw,27px);margin:0 0 18px}h3{font-size:clamp(17px,1.7vw,21px);margin:0 0 10px}p{margin:0 0 16px}ul,ol{padding-left:24px}li{margin:0 0 9px}section{scroll-margin-top:128px}.wrap{width:min(calc(100% - 56px),var(--max));margin-inline:auto}.reading{max-width:780px}.eyebrow{font-size:13px;font-weight:700;letter-spacing:.14em;color:#137a9b;text-transform:uppercase;display:inline-block;margin-bottom:10px}.lead{font-size:17px;line-height:1.85;color:#446075}.small-note{font-size:14px;color:var(--muted)}.skip-link{position:fixed;left:12px;top:-120px;z-index:200;background:#fff;padding:8px 16px}.skip-link:focus{top:12px}.site-header{position:relative;background:#fff;z-index:30;border-bottom:1px solid var(--line)}.toolbar{height:72px;display:flex;align-items:center;gap:24px}.brand{display:flex;align-items:center;gap:10px;color:var(--sea);text-decoration:none;white-space:nowrap;min-width:0}.brand img{display:block;width:auto;height:auto;max-height:38px;max-width:220px;object-fit:contain}.brand small{font-size:11px;color:#65839b;letter-spacing:.08em}.brand 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p{max-width:650px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:25px}.text-button{display:inline-flex;align-items:center;border:1px solid #c3dce8;border-radius:8px;padding:8px 20px;text-decoration:none;font-weight:700;background:white}.section{padding-block:42px}.section-alt{background:var(--wash2);border-block:1px solid var(--line)}.section-head{margin-bottom:24px;max-width:800px}.section-head p{color:var(--muted)}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:15px}.topic-card,.info-card,.feature-card{min-width:0;background:#fff;border:1px solid var(--line);border-radius:14px;padding:22px}.topic-card{text-decoration:none;display:block}.topic-card strong{font-size:18px;display:block;margin-bottom:6px;color:var(--heading)}.topic-card span{font-size:14px;color:var(--body);line-height:1.7}.topic-card:hover{border-color:#8fd9e2;box-shadow:0 7px 26px rgba(22,79,111,.07)}.editor-layout{display:grid;grid-template-columns:minmax(0,2fr) minmax(0,1fr);gap:20px}.editor-layout .feature-card:first-child{background:var(--wash)}.feature-stack{display:grid;gap:20px}.split-feature{display:grid;grid-template-columns:1fr 1fr;gap:40px;align-items:center}.split-feature.reverse> :first-child{order:2}.rule-strip{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}.rule-strip article{border-top:3px solid var(--cyan);padding:18px 0}.rule-strip .num{color:#128b9d;font-size:13px;font-weight:700;letter-spacing:.1em}.reading-path{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;list-style:none;padding:0;counter-reset:paths}.reading-path li{border-left:2px solid #8ad7e4;padding:3px 15px;counter-increment:paths}.reading-path li::before{content:'0' counter(paths);display:block;font-weight:700;color:#1787db}.page-intro{padding:50px 0 30px}.page-intro .wrap{max-width:var(--max)}.page-intro .lead{max-width:850px}.page-compact{padding-block:36px 22px}.body-section{padding-block:26px}.body-section+ 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