:root{--ink:#173548;--body:#354D5A;--muted:#667B85;--navy:#112E43;--teal:#16A6A6;--line:#DBE4E8;--paper:#F5F7F9;--soft:#EDF2F5;--a:#246DA8;--max:1200px}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--body);font:16.5px/1.8 Arial,'PingFang SC','Microsoft YaHei',sans-serif}a{color:var(--a);text-underline-offset:3px}a:hover{color:#124466}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid #16A6A6;outline-offset:3px}.container{width:min(calc(100% - 56px),var(--max));margin-inline:auto;min-width:0}.skip-link{position:absolute;z-index:50;top:-90px;left:8px;background:white;padding:8px}.skip-link:focus{top:8px}.site-header{background:white}.brandbar{min-height:70px;display:flex;align-items:center;gap:16px}.brand{display:flex;align-items:center;gap:13px;min-width:0;text-decoration:none;color:var(--ink)}.brand-image{display:flex;align-items:center;justify-content:center;min-width:0}.brand-image img{display:block;width:auto;height:auto;max-width:170px;max-height:38px;object-fit:contain}.logo-placeholder{font-weight:700;font-size:20px}.brand-copy{display:flex;flex-direction:column;line-height:1.3;white-space:nowrap}.brand-copy b{letter-spacing:.085em}.brand-copy small{font-size:12px;color:var(--muted);margin-top:4px}.register{margin-left:auto;background:var(--navy);color:white;text-decoration:none;font-weight:700;border-radius:7px;padding:7px 18px;white-space:nowrap}.register:hover{background:#246DA8;color:#fff}.desktop-nav{background:var(--navy)}.nav-items{display:flex;align-items:stretch;justify-content:space-between;gap:3px}.nav-items a{flex:1;min-width:0;text-align:center;padding:12px 6px 10px;color:#e8f1f5;text-decoration:none;font-size:15px;border-bottom:3px solid transparent;white-space:nowrap}.nav-items a:hover,.nav-items a[aria-current=page]{color:white;background:#1D455B;border-color:var(--teal);font-weight:700}.menu-toggle{display:none}.mobile-drawer{position:fixed;z-index:30;inset:0 auto 0 0;width:min(86vw,336px);background:white;transform:translateX(-105%);transition:transform .22s ease;overflow:auto;padding:19px 18px;box-shadow:6px 0 24px #0d283329;visibility:hidden}.mobile-drawer.open{transform:translateX(0);visibility:visible}.drawer-mask{position:fixed;inset:0;z-index:29;background:#0b243b8a;visibility:hidden;pointer-events:none}.drawer-mask.visible{visibility:visible;pointer-events:auto}.drawer-top{display:flex;align-items:center;justify-content:space-between;color:var(--ink);font-size:20px}.drawer-close,.menu-toggle{border:0;background:none;color:var(--navy);font-size:28px;min-width:42px;min-height:42px;cursor:pointer}.drawer-current{font-size:14px;background:var(--soft);padding:8px 12px}.drawer-group{padding:10px 0;border-top:1px solid var(--line)}.drawer-group strong{display:block;color:var(--muted);font-size:13px;margin:4px 0}.drawer-group a{display:block;text-decoration:none;color:var(--body);padding:9px 12px;border-radius:6px}.drawer-group a[aria-current=page]{background:#EAF7F5;color:#0A6363;font-weight:700}.menu-open{overflow:hidden}.noscript-nav{padding:12px 0;display:flex;flex-wrap:wrap;gap:14px}.main-content{padding-top:28px;padding-bottom:76px}.breadcrumb{font-size:13px;color:var(--muted);display:flex;align-items:center;gap:10px;margin-bottom:25px}.breadcrumb a{text-decoration:none}.eyebrow{font-weight:700;color:#0A7E7E;letter-spacing:.07em;font-size:13px}.page-intro{margin-bottom:42px;max-width:950px}.page-intro h1,.hero h1{font-size:clamp(27px,3vw,42px);line-height:1.28;letter-spacing:-.025em;color:var(--ink);margin:9px 0 18px}.page-intro p,.hero p{max-width:810px;font-size:17px}.article{max-width:790px;min-width:0}.section{margin:0 0 52px;min-width:0}.section h2,.related h2{font-size:26px;line-height:1.35;color:var(--ink);margin:0 0 18px}.section h3{font-size:20px;color:var(--ink);margin:26px 0 8px}.section p{margin:0 0 15px}.lead{font-size:18px;color:var(--ink)}.panel{background:white;border:1px solid var(--line);border-radius:12px;padding:22px 25px}.tint{background:#EAF7F5}.muted{color:var(--muted)}.hero{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);align-items:center;gap:30px;padding:32px 34px;background:white;border:1px solid var(--line);border-radius:14px;margin-bottom:53px}.hero-actions,.inline-links,.related-links{display:flex;gap:12px;flex-wrap:wrap}.hero-actions a,.inline-links a,.related-links a{display:inline-block;padding:7px 13px;border-radius:7px;background:var(--soft);text-decoration:none;font-weight:700}.hero-actions a:first-child{background:var(--navy);color:#fff}.media-frame{display:flex;align-items:center;justify-content:center;min-width:0;width:100%;margin:0;padding:8px;border-radius:12px;background:var(--soft)}.media-frame img{display:block;width:auto;height:auto;max-width:100%;max-height:var(--media-max-height,215px);object-fit:contain;object-position:center}.media-frame--hero{--media-max-height:300px}.media-frame--feature{--media-max-height:245px}.media-frame--article{--media-max-height:185px}.media-frame--rules{--media-max-height:215px}.media-frame--banner{--media-max-height:205px}.media-frame--portrait{--media-max-height:340px;max-width:310px;margin-inline:auto}.media-missing{font-size:13px;color:var(--muted);min-height:72px;border:1px dashed #b4c8d0}.feature-row,.split,.magazine,.sidebar-layout,.asym{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:30px;align-items:start}.feature-row{align-items:center}.asym{grid-template-columns:minmax(0,2fr) minmax(0,1fr)}.sidebar-layout{grid-template-columns:210px minmax(0,1fr);gap:38px}.magazine{grid-template-columns:minmax(0,1.55fr) minmax(0,.85fr)}.soft-band{background:#EDF2F5;padding:28px;border-radius:12px}.dark-band{background:var(--navy);color:#e8f1f5;padding:27px;border-radius:12px}.dark-band h2,.dark-band h3{color:#fff}.topic-index{border-top:2px solid var(--navy);display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 30px}.topic-item{border-bottom:1px solid var(--line);display:flex;gap:14px;padding:18px 0;min-width:0}.topic-item .num{font-weight:800;font-size:24px;color:#0A8484;line-height:1.25}.topic-item h3{font-size:19px;margin:0 0 4px;color:var(--ink)}.topic-item p{margin:0;font-size:15px}.topic-item a{font-weight:700}.section-kicker{font-size:12px;letter-spacing:.08em;color:#0A8181;font-weight:700;text-transform:uppercase}.note{padding:15px 18px;border-left:4px solid var(--teal);background:#EAF7F5;border-radius:0 8px 8px 0;margin:18px 0}.steps{margin:0;padding:0;list-style:none;counter-reset:step}.steps li{counter-increment:step;padding:4px 0 21px 52px;position:relative;border-left:2px solid var(--line);margin-left:16px}.steps li:last-child{border-color:transparent}.steps li::before{content:counter(step);position:absolute;left:-18px;top:0;width:34px;height:34px;border-radius:50%;background:var(--navy);color:white;display:grid;place-items:center;font-size:15px;font-weight:700}.steps strong{display:block;color:var(--ink)}.reading-nav{position:sticky;top:18px;background:white;border:1px solid var(--line);border-radius:10px;padding:18px}.reading-nav strong{display:block;color:var(--ink);margin-bottom:10px}.reading-nav a{display:block;margin:9px 0;text-decoration:none}.table-scroll{max-width:100%;overflow-x:auto;margin:20px 0;border:1px solid var(--line);border-radius:9px;background:white}.info-table{width:100%;border-collapse:collapse;min-width:550px;font-size:15px;line-height:1.55}.info-table caption{text-align:left;font-size:14px;color:var(--muted);padding:13px 14px}.info-table th,.info-table td{text-align:left;padding:12px 15px;vertical-align:top;border-bottom:1px solid var(--line)}.info-table th{background:#EDF2F5;color:var(--ink)}.info-table tr:last-child td{border-bottom:0}.concept-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.concept-grid > div{padding:20px;border-top:3px solid var(--teal);background:white}.concept-grid h3{margin:0 0 7px}.faq details{padding:15px 0;border-bottom:1px solid var(--line)}.faq summary{cursor:pointer;font-weight:700;color:var(--ink)}.faq details p{padding:8px 0 0;margin:0}.related{padding-top:24px;border-top:2px solid var(--navy);margin-top:60px}.related-links a{background:white;border:1px solid var(--line)}.site-footer{background:#0E293A;color:#c9d7df;font-size:14px;padding-top:37px}.footer-grid{display:grid;grid-template-columns:2fr 1fr;gap:44px}.site-footer h2{font-size:18px;color:white;margin:0 0 8px}.site-footer h2 small{font-size:11px;letter-spacing:.08em;margin-left:7px}.footer-links{display:grid;grid-template-columns:1fr 1fr;gap:5px 15px}.site-footer a{color:#d4ecf2}.footer-bottom{display:flex;justify-content:space-between;gap:20px;border-top:1px solid #37515e;margin-top:28px;padding:15px 0;font-size:12px}.bullet{padding-left:23px}.bullet li{margin-bottom:7px}.pullquote{border-left:4px solid #16A6A6;padding-left:18px;font-size:20px;font-weight:700;color:var(--ink);margin:25px 0}.muted-card{background:#EDF2F5;padding:17px;border-radius:10px}
@media(max-width:1024px){.container{width:calc(100% - 44px)}.hero{padding:24px}.nav-items a{font-size:14px}}@media(max-width:920px){.desktop-nav{display:none}.brandbar{height:64px;min-height:64px;justify-content:space-between}.menu-toggle{display:block}.brand-copy{display:none}.brand-image img{max-height:30px;max-width:155px}.brand{margin:auto}.register{margin-left:0;padding:6px 10px;font-size:13px}.main-content{padding-top:24px}.sidebar-layout{grid-template-columns:180px minmax(0,1fr)}}@media(min-width:921px){.mobile-drawer,.drawer-mask{display:none!important}}@media(max-width:760px){.feature-row,.split,.magazine,.sidebar-layout,.asym,.hero,.footer-grid{grid-template-columns:minmax(0,1fr)}.sidebar-layout .reading-nav{position:static;order:2}.sidebar-layout .main-article{order:1}.hero{padding:22px}.topic-index{grid-template-columns:1fr}.concept-grid{grid-template-columns:1fr 1fr}.section{margin-bottom:36px}.main-content{padding-bottom:45px}}@media(max-width:640px){body{font-size:15.5px}.container{width:calc(100% - 32px)}.main-content{padding-top:16px}.page-intro h1,.hero h1{font-size:28px}.page-intro p,.hero p{font-size:16px}.section h2{font-size:22px}.section h3{font-size:19px}.hero{padding:18px 16px;gap:18px}.panel,.soft-band,.dark-band{padding:18px}.media-frame--hero{--media-max-height:200px}.media-frame--feature{--media-max-height:180px}.media-frame--article{--media-max-height:145px}.media-frame--rules{--media-max-height:170px}.media-frame--banner{--media-max-height:130px}.media-frame--portrait{--media-max-height:280px;max-width:245px}.footer-bottom{display:block}.footer-bottom span{display:block;margin-top:6px}.concept-grid{grid-template-columns:1fr}.brandbar{gap:3px}.brand-image img{max-width:128px}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.mobile-drawer{transition:none}}
