:root{--bg:#F4F7FA;--paper:#fff;--mist:#EAF1F6;--cyan-soft:#E9F8F8;--nav:#102E46;--nav2:#163C57;--aqua:#13B8C5;--blue:#237BD3;--title:#18364B;--text:#344C60;--muted:#64798A;--line:#DCE6ED;--footer:#0B2539;--container:1200px}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:24px}body{margin:0;background:var(--bg);font:16px/1.8 Arial,"PingFang SC","Microsoft YaHei",sans-serif;color:var(--text)}body.drawer-open{overflow:hidden}a{color:#1766ae;text-decoration:none}a:hover{text-decoration:underline}button{font:inherit}img{max-width:100%}.container{width:min(calc(100% - 56px),var(--container));margin-inline:auto}main{min-height:50vh}h1,h2,h3{color:var(--title);line-height:1.4;margin:0 0 .7em}h1{font-size:clamp(32px,3.15vw,44px);letter-spacing:-.02em}h2{font-size:27px}h3{font-size:20px}p{margin:0 0 1.2em}p:last-child{margin-bottom:0}.eyebrow{color:#087f8d;font-size:13px;font-weight:bold;letter-spacing:.11em;text-transform:uppercase}.muted{color:var(--muted)}.section{margin-block:60px}.section-heading{max-width:780px;margin-bottom:26px}.section-heading p{font-size:16px}.skip-link{position:absolute;top:-100px;left:10px;background:#fff;padding:10px;z-index:300}.skip-link:focus{top:8px}:focus-visible{outline:3px solid #237BD3;outline-offset:3px}
.brand-bar{background:#fff;border-bottom:1px solid var(--line)}.brand-inner{height:72px;display:flex;align-items:center;gap:25px}.brand{display:block;min-width:0}.brand .media-frame{padding:0;background:transparent;max-width:205px}.brand .media-frame img{max-height:38px;max-width:100%;width:auto;height:auto}.brand-note{font-size:13px;color:var(--muted)}.brand-note span{color:var(--aqua);padding:0 7px}.entry-link{margin-left:auto;border-radius:9px;background:var(--nav);color:#fff;padding:6px 22px;font-weight:bold;white-space:nowrap;font-size:14px}.entry-link:hover{color:#fff;background:#174763;text-decoration:none}.desktop-nav{background:var(--nav)}.nav-row{display:grid;grid-template-columns:repeat(7,minmax(0,1fr));align-items:stretch;height:51px}.nav-row a{position:relative;display:flex;align-items:center;justify-content:center;padding:0 4px;color:#e6f4fb;font-size:14px;font-weight:500;white-space:nowrap}.nav-row a:hover,.nav-row a[aria-current=page]{color:#fff;text-decoration:none;font-weight:700;background:#1b435c}.nav-row a[aria-current=page]:after{content:"";position:absolute;left:30%;right:30%;bottom:0;height:3px;background:var(--aqua)}.menu-toggle{display:none}.mobile-drawer,.drawer-overlay,.mobile-quicklinks,.nojs-nav{display:none}
.media-frame{display:flex;align-items:center;justify-content:center;min-width:0;width:100%;padding:9px;border-radius:14px;background:var(--mist);overflow:visible}.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--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:auto}.media-frame--logo{background:transparent;padding:0;--media-limit:38px}.media-missing{width:100%;min-height:86px;display:grid;place-items:center;background:linear-gradient(120deg,#e5edf3,#f0f5f8);border:1px dashed #cbd9e4;border-radius:9px;font-size:13px;color:#718798}.media-frame--hero .media-missing{min-height:160px}
.hero{display:grid;grid-template-columns:52fr 48fr;align-items:center;gap:36px;padding:48px 0 15px}.hero-copy h1{max-width:620px}.hero-copy p{max-width:630px}.hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:25px}.btn{display:inline-flex;align-items:center;min-height:43px;padding:8px 19px;border-radius:9px;background:var(--nav);color:#fff;font-weight:bold;font-size:14px}.btn.secondary{background:#d9f4f6;color:#123c50}.btn:hover{text-decoration:none;filter:brightness(.94)}.grid-2{display:grid;grid-template-columns:1fr 1fr;gap:28px}.grid-3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}.grid-2>*,.grid-3>*,.hero>*,.feature-row>*,.content-sidebar>*{min-width:0}.index-directory{display:grid;grid-template-columns:1fr 1fr;gap:0 38px}.index-topic{padding:17px 0 21px;border-top:1px solid var(--line)}.index-topic h3{margin-bottom:6px;font-size:19px}.index-topic p{font-size:15px;margin-bottom:10px}.text-link{display:inline-block;font-size:14px;font-weight:bold;text-underline-offset:4px}.feature-grid{display:grid;grid-template-columns:2fr 1fr;gap:24px}.feature-main{background:#fff;border-left:5px solid var(--aqua);padding:29px 31px}.feature-side{display:grid;gap:16px}.feature-side article{padding:21px 22px;background:var(--mist);border-radius:12px}.feature-side h3{font-size:19px}.feature-row{display:grid;grid-template-columns:46fr 54fr;gap:35px;align-items:center}.feature-row.reverse{grid-template-columns:54fr 46fr}.feature-row.reverse .media-frame{order:2}.feature-row p{max-width:700px}.light-band{padding:32px;background:var(--cyan-soft);border-radius:14px}.rule-note{border-top:3px solid #9ad8df;background:#fff;padding:24px 22px}.rule-note:nth-child(2){margin-top:20px}.rule-note:nth-child(3){margin-top:40px}.reading-path{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:13px;counter-reset:route}.reading-path article{border-top:2px solid #1e789e;padding:15px;background:#fff}.reading-path article:before{counter-increment:route;content:"0" counter(route);font-size:13px;color:#168697;font-weight:bold;letter-spacing:.12em}.reading-path h3{margin-top:8px}.editor-note{border-top:1px solid var(--line);padding-top:20px;font-size:14px;color:var(--muted)}
.page-intro{padding-top:40px;padding-bottom:21px;border-bottom:1px solid var(--line)}.page-intro h1{font-size:36px;max-width:990px}.page-intro>p,.intro-copy{max-width:850px}.breadcrumbs{display:flex;align-items:center;gap:12px;font-size:13px;color:var(--muted);margin-bottom:22px}.anchor-nav{display:flex;flex-wrap:wrap;gap:8px;margin-top:21px}.anchor-nav a{padding:6px 12px;color:#13536d;background:#e0f1f5;border:1px solid #c9e3e7;border-radius:6px;font-size:14px}.anchor-nav a:hover{background:#c8e8ed;text-decoration:none}.article-section{margin:48px 0}.article-section p{max-width:810px}.content-sidebar{display:grid;grid-template-columns:minmax(0,1fr) 260px;gap:35px;align-items:start}.reading-column{max-width:800px}.aside-index{background:#fff;padding:22px;border-top:4px solid var(--aqua);border-radius:0 0 11px 11px}.aside-index strong{display:block;margin-bottom:12px;color:var(--title)}.aside-index a{display:block;padding:9px 0;border-bottom:1px solid var(--line);font-size:14px}.aside-index a:last-child{border:0}.lead{font-size:18px;color:#2b4c61}.info-strip{padding:18px 20px;border-left:4px solid var(--blue);background:var(--mist);margin:24px 0}.compare-table{width:100%;border-collapse:collapse;background:#fff;font-size:15px}.compare-table caption{text-align:left;font-weight:bold;color:var(--title);padding:0 0 12px}.compare-table th,.compare-table td{padding:14px 16px;border:1px solid var(--line);text-align:left;vertical-align:top}.compare-table th{background:#eaf1f6;color:var(--title)}.table-scroll{overflow-x:auto;margin:18px 0 28px}.table-scroll .compare-table{min-width:560px}.step-list{counter-reset:step;list-style:none;margin:22px 0;padding:0}.step-list li{counter-increment:step;position:relative;padding:0 0 28px 53px;border-left:1px solid #bfd7e5;margin-left:18px}.step-list li:before{content:counter(step);position:absolute;left:-18px;top:0;width:35px;height:35px;display:grid;place-items:center;border-radius:50%;background:var(--nav2);color:#fff;font-weight:bold}.step-list li:last-child{border-left:0}.step-list strong{display:block;color:var(--title)}.tag{font-weight:bold;color:#068392;font-size:13px}.article-panel{background:#fff;padding:26px;border:1px solid var(--line);border-radius:13px}.article-panel h3{font-size:19px}.wide-prose{max-width:870px}.two-col-text{columns:2;column-gap:42px}.two-col-text p{break-inside:avoid}.comparison-cards{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}.comparison-cards article{padding:21px;background:#fff;border-top:3px solid #30a9b5}.comparison-cards p{font-size:15px}.exhibit{display:grid;grid-template-columns:45fr 55fr;gap:35px;align-items:center;margin:35px 0}.exhibit:nth-of-type(even){grid-template-columns:55fr 45fr}.exhibit:nth-of-type(even) .media-frame{order:2}.faq-list details{border-bottom:1px solid var(--line);padding:15px 0}.faq-list summary{cursor:pointer;color:var(--title);font-weight:700;padding-right:15px}.faq-list p{padding:12px 0 0;margin-bottom:0;max-width:820px}.footer-links{border-top:1px solid var(--line);padding-top:26px;margin-top:48px}.footer-links h2{font-size:23px}.footer-links .link-row{display:flex;flex-wrap:wrap;gap:12px 27px}.footer-links a{font-weight:bold}.about-layout{display:grid;grid-template-columns:230px minmax(0,1fr);gap:34px}.about-main{max-width:860px}.about-aside{align-self:start;position:sticky;top:20px}.about-aside a{display:block;padding:7px 0;border-bottom:1px solid var(--line)}
.site-footer{margin-top:70px;background:var(--footer);color:#DCECF5;padding:44px 0 18px}.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr;gap:50px}.footer-brand{color:#fff;font-size:22px;font-weight:bold}.footer-brand span{display:block;font-size:11px;letter-spacing:.18em;color:#91ccd2}.site-footer p{font-size:14px;max-width:580px}.footer-disclaimer{color:#bbd0dd}.site-footer nav strong{display:block;margin-bottom:10px;color:#fff}.site-footer nav a{display:block;color:#DCECF5;font-size:14px;padding:3px 0}.footer-bottom{border-top:1px solid #31546a;margin-top:26px;padding-top:14px;display:flex;justify-content:space-between;gap:20px;font-size:12px;color:#bdd1dd}.footer-bottom a{color:#bdd1dd}
@media(max-width:1200px){.container{width:calc(100% - 44px)}}
@media(max-width:920px){.brand-inner{height:63px;justify-content:space-between;gap:10px}.brand-note,.desktop-nav{display:none}.menu-toggle{display:flex;flex-direction:column;justify-content:center;align-items:center;gap:5px;flex:0 0 40px;width:40px;height:40px;border:1px solid var(--line);border-radius:9px;background:#fff;cursor:pointer}.menu-toggle span{display:block;width:19px;height:2px;background:var(--nav)}.brand{margin-inline:auto}.brand .media-frame{max-width:175px}.brand .media-frame img{max-height:30px}.entry-link{margin-left:0;padding:7px 11px;font-size:12px;min-height:38px;display:flex;align-items:center}.mobile-drawer{display:block;position:fixed;z-index:210;top:0;bottom:0;left:0;width:min(86vw,340px);overflow-y:auto;background:#fff;padding:20px 23px;transform:translateX(-105%);visibility:hidden;transition:transform .22s ease,visibility .22s;box-shadow:4px 0 30px #0002}.drawer-open .mobile-drawer{transform:translateX(0);visibility:visible}.drawer-overlay{display:block;position:fixed;inset:0;background:rgb(12 30 45 / .57);z-index:200;opacity:0;visibility:hidden;pointer-events:none;transition:opacity .22s,visibility .22s}.drawer-open .drawer-overlay{opacity:1;visibility:visible;pointer-events:auto}.drawer-head{display:flex;justify-content:space-between;align-items:center;padding-bottom:18px;border-bottom:1px solid var(--line);color:var(--title)}.drawer-close{background:#edf4f7;border:0;border-radius:7px;font-size:28px;line-height:1;width:40px;height:40px;cursor:pointer}.drawer-group{padding:18px 0 12px;border-bottom:1px solid var(--line)}.drawer-label{display:block;font-size:12px;color:#658498;font-weight:bold;margin-bottom:9px}.drawer-group a{display:block;padding:10px 5px;color:var(--title);font-weight:600}.mobile-quicklinks{display:flex;gap:18px;justify-content:center;flex-wrap:wrap;padding:24px 0 0;font-size:13px}.nojs-nav{display:flex;flex-wrap:wrap;gap:10px;padding:12px 20px;background:#eaf1f6}.nojs-nav a{padding:4px 6px}.hero{gap:23px}.index-directory{gap:0 20px}}
@media(max-width:760px){.container{width:calc(100% - 44px)}.hero,.feature-grid,.feature-row,.feature-row.reverse,.content-sidebar,.grid-2,.exhibit,.exhibit:nth-of-type(even),.about-layout{grid-template-columns:minmax(0,1fr)}.feature-row.reverse .media-frame,.exhibit:nth-of-type(even) .media-frame{order:0}.hero{padding-top:35px}.hero .media-frame{max-width:650px}.feature-row{gap:19px}.feature-grid{gap:14px}.reading-path{grid-template-columns:1fr 1fr}.comparison-cards{grid-template-columns:1fr}.grid-3{grid-template-columns:1fr 1fr}.about-aside{position:static;order:2}.footer-grid{grid-template-columns:1fr 1fr;gap:24px}.footer-grid>div{grid-column:1/-1}.two-col-text{columns:1}.aside-index{max-width:100%}.page-intro{padding-top:30px}}
@media(max-width:640px){body{font-size:15px;line-height:1.77}.container{width:calc(100% - 32px)}h1{font-size:29px}.page-intro h1{font-size:27px}h2{font-size:22px}h3{font-size:18px}.section{margin-block:37px}.article-section{margin:36px 0}.brand .media-frame{max-width:145px}.brand .media-frame img{max-height:29px}.hero{gap:17px}.hero-actions{margin-top:18px}.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}.index-directory{grid-template-columns:1fr}.index-topic{padding:13px 0 17px}.light-band{padding:22px 16px}.feature-main{padding:23px 20px}.grid-3{grid-template-columns:1fr}.rule-note:nth-child(n){margin-top:0}.rule-note{padding:20px}.reading-path{gap:8px}.reading-path article{padding:12px}.reading-path h3{font-size:17px}.article-panel{padding:19px}.site-footer{margin-top:42px;padding-top:34px}.footer-grid{gap:26px}.footer-bottom{flex-wrap:wrap}.compare-table th,.compare-table td{padding:11px}.intro-copy{font-size:15px}}
@media(max-width:375px){.brand .media-frame{max-width:128px}.brand-inner{gap:7px}.entry-link{padding-inline:8px}.menu-toggle{flex-basis:40px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;animation:none!important;transition:none!important}}