:root{--bg:#F6FAFC;--surface:#fff;--soft:#EAF6FA;--soft2:#EDF4F8;--cyan:#25C8D1;--sky:#25B6E8;--blue:#1787DB;--navy:#174B78;--title:#183A56;--text:#31485D;--muted:#687D8E;--line:#DCE9F0;--footer:#123653;--width:1180px}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:24px}body{margin:0;font-family:Arial,"PingFang SC","Microsoft YaHei",sans-serif;background:var(--bg);color:var(--text);line-height:1.8;overflow-x:hidden}a{color:var(--navy);text-decoration-color:#94B8C8;text-underline-offset:4px}a:hover{color:#116CA6;text-decoration-color:currentColor}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--blue);outline-offset:3px}button{font:inherit;cursor:pointer}.wrap{width:min(calc(100% - 56px),var(--width));margin-inline:auto}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip-link{position:absolute;left:12px;top:-80px;z-index:200;background:#fff;padding:8px 15px}.skip-link:focus{top:8px}
h1,h2,h3{color:var(--title);line-height:1.35;letter-spacing:-.018em}h1{font-size:35px;margin:0 0 18px}h2{font-size:26px;margin:0 0 18px}h3{font-size:20px;margin:0 0 12px}p{margin:0 0 16px}section{scroll-margin-top:28px}.eyebrow{display:block;text-transform:uppercase;letter-spacing:.11em;color:#187C9A;font-size:13px;font-weight:700;margin-bottom:12px}.section-intro{color:var(--muted);max-width:760px}.lead{font-size:17px;max-width:810px;color:#425F73}.section{margin-block:56px}.section-head{margin-bottom:22px}.section-head p{max-width:740px}
.site-header{background:white;border-bottom:1px solid var(--line)}.masthead{height:72px;display:flex;align-items:center;gap:20px}.brand{display:flex;align-items:center;gap:8px;min-width:0;text-decoration:none}.brand-fallback{font-weight:800;color:var(--title);white-space:nowrap;font-size:21px;line-height:1.05}.brand-fallback small{display:block;font-weight:600;letter-spacing:.09em;font-size:9px;color:var(--muted);margin-top:5px}.brand:has(img) .brand-fallback{display:none}.masthead-tagline{margin-left:auto;color:var(--muted);font-size:14px}.entry-button{margin-left:20px;display:inline-flex;align-items:center;justify-content:center;min-height:40px;padding:4px 23px;border-radius:9px;color:#fff;background:var(--navy);text-decoration:none;font-size:14px;font-weight:700;white-space:nowrap}.entry-button:hover{background:#0E648D;color:white}.desktop-nav{background:var(--navy)}.nav-inner{display:flex;align-items:center;justify-content:space-between;gap:5px;min-height:49px}.nav-inner a{display:inline-block;padding:10px 12px;color:#e6f5fc;font-size:14px;white-space:nowrap;text-decoration:none;border-bottom:3px solid transparent}.nav-inner a:hover,.nav-inner a.is-active{border-color:var(--cyan);color:#fff;font-weight:700}.menu-toggle{display:none}.drawer-overlay,.site-drawer{display:none}.quick-topics{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px;margin-block:24px 8px}.quick-topics>div{padding:12px 16px;background:#fff;border:1px solid var(--line);border-radius:12px;font-size:13px;display:flex;gap:11px;align-items:center;flex-wrap:wrap}.quick-topics strong{color:var(--navy);margin-right:4px}.quick-topics a{text-decoration:none;white-space:nowrap}
.media{display:flex;justify-content:center;align-items:center;width:100%;min-width:0;overflow:hidden;border-radius:14px;background:var(--soft);border:1px solid var(--line)}.media img{display:block;width:auto;height:auto;max-width:100%;max-height:100%;object-fit:contain;object-position:center}.media--logo{max-height:38px;max-width:220px;border:0;background:transparent;border-radius:0;min-height:30px}.media--logo img{max-height:38px}.media--hero{height:min(26vw,330px);min-height:250px}.media--feature{height:250px}.media--card{height:170px}.media--banner{height:220px}.media--mobile{height:350px;max-width:320px}.media--missing{background:linear-gradient(135deg,#eaf6fa,#f5fbfd);position:relative}.media--missing:not(.media--logo)::after{content:"";width:46px;height:46px;border:2px solid #c9e2eb;border-radius:50%;position:absolute}.media--logo.media--missing{display:none}
.hero{padding:42px 0 24px;display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);align-items:center;gap:46px}.hero h1{font-size:41px}.hero p{max-width:615px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:24px}.button{display:inline-flex;min-height:44px;align-items:center;justify-content:center;padding:8px 19px;border-radius:9px;background:var(--navy);color:#fff;text-decoration:none;font-size:15px;font-weight:700}.button:hover{background:#12669A;color:white}.button--light{background:#e4f5fa;color:var(--navy);border:1px solid #b6dbe9}.button--light:hover{background:#d4edf7;color:#0b507c}.panel{background:#fff;border:1px solid var(--line);border-radius:15px;padding:25px}.panel--tint{background:var(--soft)}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.topic-card{display:block;text-decoration:none;border:1px solid var(--line);background:white;border-radius:14px;padding:21px;min-width:0;transition:border-color .2s,transform .2s}.topic-card:hover{border-color:#86bfce;transform:translateY(-2px)}.topic-card strong{display:block;font-size:18px;color:var(--title);margin-bottom:6px}.topic-card span{display:block;color:var(--muted);font-size:14px;line-height:1.7}.topic-card em{font-style:normal;color:#197f9f;font-size:13px;display:block;margin-top:10px;font-weight:700}.editorial-grid{display:grid;grid-template-columns:2fr 1fr;gap:18px}.editorial-main{background:var(--soft);border-radius:16px;padding:30px}.editorial-side{display:grid;gap:15px}.editorial-side article{background:white;border:1px solid var(--line);padding:22px;border-radius:14px}.feature-split{display:grid;grid-template-columns:1fr 1fr;gap:36px;align-items:center}.feature-split.reverse .media{order:-1}.feature-split>div,.feature-split>article{min-width:0}.feature-split .media{min-width:0}.mini-list{padding-left:20px;margin-top:10px}.mini-list li{margin-block:7px}.knowledge-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.knowledge-grid article{border-top:3px solid var(--cyan);background:white;padding:24px;border-radius:0 0 12px 12px}.reading-path{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px;counter-reset:step}.reading-path div{background:var(--soft2);padding:20px;border-radius:13px}.reading-path div::before{counter-increment:step;content:"0" counter(step);display:block;color:#0c91a2;font-size:14px;font-weight:800;margin-bottom:6px}.reading-path strong{display:block;color:var(--title)}.note{border-left:3px solid var(--cyan);padding:15px 19px;background:var(--soft2);font-size:14px;border-radius:0 10px 10px 0}.article-head{padding:46px 0 24px;border-bottom:1px solid var(--line);margin-bottom:36px}.article-head .lead{margin-bottom:0}.article-layout{display:grid;grid-template-columns:minmax(0,780px) minmax(0,240px);gap:55px;align-items:start}.article-body{max-width:780px;min-width:0}.article-body section{margin:0 0 43px}.article-body h2{margin-bottom:18px}.article-body p,.prose p{line-height:1.83}.glossary{background:#e9f5fa;border:1px solid var(--line);padding:21px;border-radius:14px;position:sticky;top:20px}.glossary dl{margin:0}.glossary dt{font-weight:700;color:var(--title);margin-top:13px}.glossary dd{font-size:14px;margin:2px 0 10px;color:var(--text)}.article-narrow{max-width:850px;margin-inline:auto}.page-sections>section{margin-bottom:50px}.data-table{overflow-x:auto;max-width:100%;border:1px solid var(--line);border-radius:12px;background:white}.data-table table{width:100%;border-collapse:collapse;min-width:580px;font-size:15px;line-height:1.7}.data-table th,.data-table td{padding:13px 16px;text-align:left;vertical-align:top;border-bottom:1px solid var(--line)}.data-table th{background:var(--soft);color:var(--title)}.data-table tr:last-child td{border-bottom:0}.numbered{counter-reset:part;list-style:none;padding:0;display:grid;gap:12px}.numbered li{counter-increment:part;border:1px solid var(--line);border-radius:12px;background:white;padding:16px 19px 16px 58px;position:relative}.numbered li::before{content:counter(part);position:absolute;left:18px;top:16px;background:var(--soft);color:var(--navy);width:28px;height:28px;line-height:28px;text-align:center;border-radius:50%;font-weight:bold}.matrix-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:17px}.matrix-grid article{padding:25px;background:white;border:1px solid var(--line);border-radius:14px}.matrix-grid article:first-child{border-top:4px solid var(--cyan)}.matrix-grid article:nth-child(2){border-top:4px solid var(--blue)}.matrix-grid article:last-child{border-top:4px solid #7bb9c6}.gallery-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.gallery-grid figure{margin:0;padding:15px;border:1px solid var(--line);border-radius:15px;background:white}.gallery-grid figcaption{padding:14px 5px 2px;font-size:14px;color:var(--muted)}.gallery-grid figcaption strong{display:block;color:var(--title);font-size:18px;margin-bottom:4px}.anchor-nav{display:flex;flex-wrap:wrap;gap:10px;margin-block:18px 28px}.anchor-nav a{display:inline-block;background:#e3f2f7;padding:8px 14px;border-radius:8px;font-size:14px;text-decoration:none}.faq-list{border-top:1px solid var(--line)}.faq-list details{border-bottom:1px solid var(--line);background:transparent;padding:14px 6px}.faq-list summary{font-weight:700;color:var(--title);cursor:pointer;padding-right:20px}.faq-list p{margin:12px 24px 3px 0;color:var(--text)}.related{border-top:1px solid var(--line);padding-top:28px;margin-block:42px 58px}.related h2{font-size:23px}.related-links{display:flex;gap:13px;flex-wrap:wrap}.related-links a{border:1px solid #c7dfe9;border-radius:10px;background:white;padding:11px 16px;text-decoration:none}.related-links a:hover{background:var(--soft)}.service-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}.service-grid article{background:white;padding:22px;border:1px solid var(--line);border-radius:12px}.site-footer{margin-top:40px;background:var(--footer);color:#eaf7ff;padding:42px 0 15px}.footer-grid{display:grid;grid-template-columns:1.3fr 1fr;gap:60px}.footer-brand{font-size:22px;color:#fff;text-decoration:none;font-weight:bold}.footer-brand small{display:block;font-size:11px;letter-spacing:.12em;font-weight:normal}.site-footer h2{font-size:18px;color:#fff}.site-footer p{color:#e2f0f5}.site-footer .fine-print{font-size:13px;max-width:550px;opacity:.85}.footer-links{display:grid;grid-template-columns:repeat(3,1fr);gap:6px 20px}.site-footer a{color:#eaf7ff}.footer-bottom{display:flex;justify-content:space-between;border-top:1px solid #41617a;margin-top:30px;padding-top:16px;font-size:12px;color:#c8dbe8}.mobile-bottom{display:none}.back-top{position:fixed;right:25px;bottom:25px;border:0;background:var(--navy);color:#fff;border-radius:12px;width:42px;height:42px;z-index:20}.back-top[hidden]{display:none}
@media(max-width:980px){.wrap{width:min(calc(100% - 44px),var(--width))}.masthead{height:64px;justify-content:space-between}.menu-toggle{display:flex;width:40px;height:40px;flex-direction:column;align-items:center;justify-content:center;gap:5px;border:1px solid var(--line);background:#fff;border-radius:8px;flex:0 0 40px}.menu-toggle span{width:19px;height:2px;background:var(--navy);border-radius:2px}.brand{position:absolute;left:50%;transform:translateX(-50%);max-width:43%;justify-content:center}.brand-fallback{font-size:19px}.masthead-tagline,.desktop-nav{display:none}.entry-button{margin-left:auto;min-height:39px;padding-inline:13px}.media--logo,.media--logo img{max-height:30px}.drawer-overlay{display:block;position:fixed;inset:0;background:rgba(11,37,56,.48);z-index:80;visibility:hidden;opacity:0;pointer-events:none;transition:opacity .2s,visibility .2s}.site-drawer{display:flex;flex-direction:column;position:fixed;inset:0 auto 0 0;width:min(86vw,344px);background:white;z-index:90;padding:18px 20px 36px;overflow-y:auto;visibility:hidden;transform:translateX(-105%);transition:transform .22s,visibility .22s;pointer-events:none}.drawer-open{overflow:hidden}.drawer-open .drawer-overlay{visibility:visible;opacity:1;pointer-events:auto}.drawer-open .site-drawer{visibility:visible;transform:translateX(0);pointer-events:auto}.drawer-top{display:flex;justify-content:space-between;align-items:center;font-size:19px;font-weight:bold;color:var(--title);margin-bottom:10px}.drawer-close{font-size:28px;line-height:1;width:40px;height:40px;border:0;background:var(--soft);border-radius:8px;color:var(--navy)}.drawer-label{font-size:12px;color:var(--muted);font-weight:700;margin:18px 0 6px}.site-drawer>a{padding:10px 12px;text-decoration:none;color:var(--text);border-radius:8px}.site-drawer>a.is-active{background:var(--soft);color:var(--navy);font-weight:bold}.quick-topics{grid-template-columns:1fr;gap:8px}.hero{gap:28px}.hero h1{font-size:35px}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.article-layout{grid-template-columns:minmax(0,1fr)}.glossary{position:static;max-width:780px}.footer-links{grid-template-columns:repeat(2,1fr)}}
@media(max-width:760px){.hero{grid-template-columns:1fr;padding:25px 0 12px}.hero .media{order:-1}.feature-split{grid-template-columns:1fr;gap:22px}.feature-split.reverse .media{order:0}.editorial-grid{grid-template-columns:1fr}.editorial-side{grid-template-columns:repeat(2,minmax(0,1fr))}.matrix-grid,.knowledge-grid{grid-template-columns:1fr}.reading-path{grid-template-columns:repeat(2,minmax(0,1fr))}.footer-grid{grid-template-columns:1fr;gap:22px}.media--hero{height:220px;min-height:0}.media--feature{height:190px}.media--banner{height:155px}}
@media(max-width:640px){.wrap{width:calc(100% - 32px)}body{font-size:15px;line-height:1.76}h1{font-size:27px}h2{font-size:22px}h3{font-size:18px}.hero h1{font-size:29px}.lead{font-size:15px}.section{margin-block:36px}.article-head{padding:29px 0 20px;margin-bottom:26px}.panel{padding:18px}.topic-grid{grid-template-columns:1fr 1fr;gap:10px}.topic-card{padding:15px}.topic-card strong{font-size:16px}.topic-card span{font-size:13px}.editorial-main{padding:20px}.editorial-side{grid-template-columns:1fr}.gallery-grid,.service-grid{grid-template-columns:1fr}.reading-path{gap:9px}.reading-path div{padding:14px}.quick-topics>div{padding:10px 12px}.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--mobile{height:290px;max-width:250px}.media--logo,.media--logo img{max-height:29px}.brand-fallback{font-size:17px}.site-footer{padding-bottom:95px}.mobile-bottom{display:grid;grid-template-columns:repeat(4,1fr);position:fixed;left:0;right:0;bottom:0;z-index:30;background:white;border-top:1px solid var(--line);padding:7px 4px calc(7px + env(safe-area-inset-bottom))}.mobile-bottom a{text-align:center;color:var(--navy);font-size:13px;font-weight:700;text-decoration:none;padding:5px 0}.back-top{bottom:85px;right:14px}.footer-bottom{gap:15px;flex-wrap:wrap}.article-body section{margin-bottom:32px}}
@media(max-height:540px) and (max-width:640px){.mobile-bottom{position:static}.site-footer{padding-bottom:18px}.back-top{bottom:15px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;animation:none!important;transition:none!important}}

.nojs-nav{display:flex;flex-wrap:wrap;gap:9px;padding-block:12px}.nojs-nav a{background:#fff;border:1px solid var(--line);border-radius:8px;padding:5px 12px;text-decoration:none}.nojs-nav a.is-active{font-weight:bold;background:var(--soft)}