:root{--bg:#F4F7FA;--white:#fff;--pale:#EAF1F6;--aqua:#E9F8F8;--navy:#102E46;--deep:#163C57;--cyan:#13B8C5;--blue:#237BD3;--title:#18364B;--text:#344C60;--muted:#64798A;--line:#DCE6ED;--footer:#0B2539;--max:1200px}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:20px}body{margin:0;background:var(--bg);color:var(--text);font:16px/1.8 Arial,'PingFang SC','Microsoft YaHei',sans-serif;overflow-x:hidden}a{color:#1669AE;text-decoration:none}a:hover{text-decoration:underline}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,p,figure{margin-top:0}h1,h2,h3{line-height:1.38;color:var(--title)}h1{font-size:clamp(27px,3.2vw,42px);letter-spacing:-.02em}h2{font-size:clamp(21px,2.2vw,28px)}h3{font-size:20px}p{margin-bottom:17px}small{font-size:.77em}.wrap{width:min(calc(100% - 56px),var(--max));margin-inline:auto}.site-main{min-height:55vh}.section{margin-block:60px}.section-tight{margin-block:40px}.section-head{margin-bottom:22px}.eyebrow{color:#087D89;font-size:13px;font-weight:800;letter-spacing:.11em;text-transform:uppercase}.lead{font-size:18px;color:#426079;max-width:790px}.muted{color:var(--muted)}.skip-link{position:absolute;top:-100px;left:8px;z-index:100;background:#fff;padding:8px}.skip-link:focus{top:8px}.brand-bar{background:#fff}.brand-inner{height:72px;display:flex;align-items:center;gap:18px}.brand{display:flex;align-items:center;gap:10px;flex-shrink:0;color:var(--title)}.brand:hover{text-decoration:none}.brand-name{font-size:18px;font-weight:800;line-height:1.1;white-space:nowrap}.brand-name small{display:block;font-size:9px;letter-spacing:2px;margin-top:5px}.brand-subtitle{color:var(--muted);font-size:13px}.entry-link{margin-left:auto;display:inline-flex;align-items:center;justify-content:center;padding:8px 17px;border-radius:9px;background:var(--deep);color:#fff;white-space:nowrap;font-size:14px;font-weight:700}.entry-link:hover{background:#0D6580;text-decoration:none}.desktop-nav{background:var(--navy)}.nav-row{display:flex;align-items:center;justify-content:space-between;gap:8px;min-height:50px}.nav-row a{color:#E5F1F7;position:relative;display:inline-flex;align-items:center;justify-content:center;flex:1;white-space:nowrap;font-weight:600;font-size:14px;padding:11px 7px}.nav-row a:hover{color:#fff;text-decoration:none}.nav-row a[aria-current="page"]{color:#fff;font-weight:800}.nav-row a[aria-current="page"]::after{content:'';height:3px;position:absolute;bottom:0;left:25%;right:25%;background:var(--cyan)}.menu-toggle,.no-js-nav,.drawer-backdrop,.mobile-drawer,.mobile-shortcuts{display:none}.media-frame{display:flex;justify-content:center;align-items:center;min-width:0;margin:0;padding:8px;background:var(--pale);border-radius:14px;overflow:hidden}.media-frame img{display:block;width:auto;height:auto;max-width:100%;max-height:var(--media-limit,220px);object-fit:contain;object-position:center}.media-frame--logo{padding:0;background:transparent;border-radius:0}.media-frame--logo img{max-height:38px;max-width:115px}.media-frame--hero{--media-limit:310px}.media-frame--feature{--media-limit:250px}.media-frame--card{--media-limit:185px}.media-frame--banner{--media-limit:210px}.media-frame--mobile{--media-limit:350px;max-width:320px;margin-inline:auto}.media-missing{min-height:100px;border:1px dashed #bfd1dd;color:#64798A;font-size:13px;text-align:center}.media-frame--logo.media-missing{min-height:32px;max-width:95px}.media-frame--hero.media-missing{min-height:210px}.media-frame--feature.media-missing{min-height:145px}.media-frame--card.media-missing{min-height:105px}.hero{padding:54px 0 20px}.hero-grid{display:grid;grid-template-columns:minmax(0,1.08fr) minmax(0,1fr);gap:36px;align-items:center}.hero h1{max-width:620px}.hero p{max-width:620px}.button-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:25px}.btn{display:inline-flex;justify-content:center;align-items:center;min-height:44px;padding:10px 19px;border-radius:9px;background:var(--deep);color:#fff;font-weight:700;font-size:15px}.btn--line{background:#fff;border:1px solid var(--line);color:var(--title)}.btn:hover{text-decoration:none;filter:brightness(.95)}.directory{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));column-gap:40px}.directory a{border-top:1px solid var(--line);padding:20px 0 23px;color:var(--text);display:block}.directory a:hover{text-decoration:none}.directory b{display:block;font-size:19px;color:var(--title);margin-bottom:7px}.directory span{display:block;font-size:15px}.directory em{display:block;color:#117e91;font-size:13px;font-style:normal;font-weight:700;margin-top:7px}.focus-grid{display:grid;grid-template-columns:minmax(0,2fr) minmax(0,1fr);gap:22px}.focus-main{padding:32px;background:var(--deep);color:#eaf5fc;border-radius:14px}.focus-main h3{font-size:27px;color:#fff}.focus-side{display:grid;gap:16px}.mini-article{background:#fff;padding:23px;border-top:3px solid var(--cyan)}.mini-article h3{font-size:20px}.split{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.15fr);gap:36px;align-items:center}.split--reverse{grid-template-columns:minmax(0,1.15fr) minmax(0,1fr)}.split--reverse>:first-child{order:2}.split--reverse>:last-child{order:1}.readable{max-width:790px}.feature-band{background:#fff;padding:32px;border:1px solid var(--line);border-radius:14px}.rule-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;align-items:start}.rule-note{padding:23px 20px;background:#fff;border:1px solid var(--line);border-radius:12px}.rule-note:nth-child(2){margin-top:20px}.rule-note:nth-child(3){margin-top:40px}.steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px}.step{border-top:4px solid var(--cyan);padding:17px 16px;background:#fff}.step b{display:block;color:#11829b;font-size:13px;margin-bottom:5px}.editor-note{border-left:4px solid var(--cyan);padding:20px 24px;background:var(--aqua)}.page-intro{padding:44px 0 16px}.page-intro h1{font-size:clamp(25px,2.8vw,36px);margin-bottom:17px}.page-intro .lead{margin-bottom:0}.crumbs{color:var(--muted);font-size:13px;margin-bottom:14px}.crumbs a{color:#276c91}.topic-nav{display:flex;flex-wrap:wrap;gap:9px;margin-top:28px}.topic-nav a{padding:8px 15px;border-radius:7px;background:#fff;border:1px solid var(--line);font-size:14px;font-weight:700}.article-grid{display:grid;grid-template-columns:minmax(0,1fr) 260px;gap:34px;align-items:start}.article{max-width:800px}.article section{margin-bottom:46px}.article p{line-height:1.82}.article h2{padding-top:4px}.article h3{margin-top:23px}.fact-index{background:#fff;padding:22px;border:1px solid var(--line);border-radius:12px}.fact-index h2{font-size:19px}.fact-index a{display:block;padding:9px 0;border-bottom:1px solid var(--line);font-size:14px}.fact-index p{font-size:14px}.table-scroll{max-width:100%;overflow-x:auto;border:1px solid var(--line);border-radius:10px;background:#fff}.info-table{width:100%;border-collapse:collapse;min-width:560px;text-align:left;font-size:15px}.info-table caption{font-weight:700;color:var(--title);text-align:left;padding:17px}.info-table th{background:var(--pale);color:var(--title);white-space:normal}.info-table td,.info-table th{border-bottom:1px solid var(--line);padding:13px 16px;vertical-align:top}.info-table tr:last-child td{border-bottom:0}.timeline{border-left:2px solid var(--cyan);padding-left:26px}.timeline>div{position:relative;margin:0 0 24px}.timeline>div:before{position:absolute;left:-34px;top:9px;content:'';width:13px;height:13px;background:var(--cyan);border:2px solid #fff;border-radius:50%}.timeline strong{color:var(--title)}.callout{padding:22px 25px;background:var(--aqua);border-left:4px solid var(--cyan);margin-block:27px}.matrix{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.matrix>article{background:#fff;border:1px solid var(--line);padding:23px;border-radius:10px}.matrix h3{font-size:20px}.gallery{display:grid;grid-template-columns:1.1fr .9fr;gap:28px;align-items:center}.gallery:nth-child(even){grid-template-columns:.9fr 1.1fr}.gallery:nth-child(even)>.media-frame{order:2}.gallery:nth-child(even)>.gallery-text{order:1}.faq{border-top:1px solid var(--line);margin-top:18px}.faq details{border-bottom:1px solid var(--line);background:rgba(255,255,255,.63);padding:0 18px}.faq summary{cursor:pointer;color:var(--title);font-weight:700;padding:17px 0}.faq details p{padding:0 0 16px;margin:0}.related-links{margin-block:52px}.related-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.related-grid a{position:relative;padding:22px 32px 22px 20px;border:1px solid var(--line);background:#fff;border-radius:10px;color:var(--text)}.related-grid strong{display:block;color:var(--title);margin-bottom:7px}.related-grid span{font-size:14px}.related-grid .link-arrow{position:absolute;right:17px;top:19px;font-size:18px}.aside-layout{display:grid;grid-template-columns:230px minmax(0,1fr);gap:40px;align-items:start}.aside-layout>.fact-index{position:sticky;top:16px}.content-panel{background:#fff;padding:30px;border:1px solid var(--line);border-radius:12px}.site-footer{background:var(--footer);color:#dcecf5;padding-top:44px}.footer-layout{display:grid;grid-template-columns:2fr 1fr;gap:60px}.footer-layout p{max-width:650px;color:#dcecf5;font-size:14px}.footer-brand{color:#fff;font-weight:800;font-size:22px}.footer-brand 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@media(max-width:1024px){.wrap{width:min(calc(100% - 44px),var(--max))}.brand-subtitle{display:none}.section{margin-block:48px}.hero-grid{gap:24px}.article-grid{grid-template-columns:minmax(0,1fr) 210px;gap:25px}}
@media(max-width:920px){.brand-inner{height:64px;justify-content:space-between;gap:10px}.menu-toggle{display:flex;order:-1;flex:0 0 40px;width:40px;height:40px;flex-direction:column;justify-content:center;align-items:center;gap:5px;background:transparent;border:1px solid var(--line);border-radius:9px;cursor:pointer}.menu-toggle span{display:block;width:20px;height:2px;background:var(--navy)}.brand{margin-inline:auto;min-width:0}.brand-name{display:none}.media-frame--logo img{max-height:30px;max-width:145px}.entry-link{margin-left:0;min-height:40px;padding:7px 10px;font-size:13px}.desktop-nav{display:none}.no-js-nav{display:flex;flex-wrap:wrap;gap:8px;padding-top:10px;padding-bottom:10px}.no-js-nav a{padding:5px 11px;background:#eaf1f6;font-size:13px}.js-enabled .no-js-nav{display:none}.drawer-backdrop{display:block;position:fixed;inset:0;z-index:90;background:rgba(6,26,42,.58);visibility:hidden;opacity:0;pointer-events:none;transition:opacity .2s,visibility .2s}.drawer-backdrop.active{visibility:visible;opacity:1;pointer-events:auto}.mobile-drawer{display:block;position:fixed;inset:0 auto 0 0;z-index:91;width:min(86vw,340px);background:#fff;transform:translateX(-105%);visibility:hidden;transition:transform .25s,visibility .25s;overflow-y:auto;overscroll-behavior:contain}.mobile-drawer.open{transform:translateX(0);visibility:visible}.menu-open{overflow:hidden}.drawer-head{display:flex;justify-content:space-between;align-items:center;padding:15px 19px;border-bottom:1px solid var(--line)}.drawer-close{width:40px;height:40px;border:1px solid var(--line);background:#fff;border-radius:8px;font-size:26px;cursor:pointer}.drawer-section{padding:12px 20px;border-bottom:1px solid var(--line)}.drawer-section b{display:block;color:var(--muted);font-size:12px;margin:7px 0}.drawer-section a{display:block;color:var(--title);padding:11px 7px;font-weight:600}.mobile-shortcuts{display:flex;justify-content:space-between;gap:10px;padding:20px 0;flex-wrap:wrap}.mobile-shortcuts a{font-size:13px;font-weight:700}}
@media(max-width:760px){.hero-grid,.split,.split--reverse,.focus-grid,.article-grid,.gallery,.gallery:nth-child(even),.aside-layout{grid-template-columns:1fr}.split--reverse>:first-child,.split--reverse>:last-child,.gallery:nth-child(even)>.media-frame,.gallery:nth-child(even)>.gallery-text{order:initial}.hero{padding-top:34px}.directory{column-gap:24px}.article-grid .fact-index{order:-1}.aside-layout>.fact-index{position:static;order:2}.aside-layout>.content-panel{order:1}.matrix,.rule-grid,.steps,.related-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.rule-note:nth-child(n){margin-top:0}.footer-layout{grid-template-columns:1fr;gap:20px}.focus-side{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:640px){.wrap{width:calc(100% - 32px)}body{font-size:15px;line-height:1.78}.section{margin-block:36px}.hero{padding-top:29px}.lead{font-size:16px}.hero h1{font-size:30px}.page-intro{padding-top:30px}.page-intro h1{font-size:27px}.directory,.matrix,.rule-grid,.steps,.related-grid,.focus-side{grid-template-columns:1fr}.feature-band,.focus-main,.content-panel{padding:19px}.directory a{padding:15px 0}.gallery{gap:15px}.media-frame--hero{--media-limit:205px}.media-frame--feature{--media-limit:185px}.media-frame--card{--media-limit:145px}.media-frame--banner{--media-limit:135px}.media-frame--mobile{--media-limit:285px;max-width:250px}.media-frame--logo img{max-height:30px}.footer-bottom{flex-direction:column;gap:3px}.topic-nav a{padding:7px 11px}.steps{gap:10px}.section-head{margin-bottom:13px}}
@media(max-width:380px){.entry-link{font-size:12px;padding-inline:8px}.brand-inner{gap:7px}.media-frame--logo img{max-width:120px}.mobile-shortcuts{gap:8px}.mobile-shortcuts a{font-size:12px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}