:root{--bg:#f4f7fa;--white:#fff;--mist:#eaf1f6;--aqua:#e9f8f8;--navy:#102e46;--deep:#163c57;--teal:#13b8c5;--blue:#237bd3;--head:#18364b;--ink:#344c60;--muted:#64798a;--line:#dce6ed;--max:1200px}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:26px}body{margin:0;background:var(--bg);font-family:Arial,'PingFang SC','Microsoft YaHei',sans-serif;color:var(--ink);font-size:16px;line-height:1.8;overflow-wrap:break-word}img{max-width:100%;height:auto}a{color:#145e99;text-decoration:none}a:hover{color:#087e99}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid #2e9cc9;outline-offset:3px}h1,h2,h3{color:var(--head);line-height:1.38;letter-spacing:-.025em}h1{font-size:35px;margin:.2em 0 .55em}h2{font-size:26px;margin:0 0 20px}h3{font-size:20px;margin:0 0 10px}p{margin:0 0 17px}ul,ol{padding-left:1.45em}li{margin-bottom:9px}.container{width:min(calc(100% - 56px),var(--max));margin:0 auto}.skip-link{position:absolute;top:-100px;left:12px;background:#fff;z-index:1000;padding:8px}.skip-link:focus{top:8px}.site-header{background:var(--navy);position:relative;z-index:30}.brand-bar{background:#fff;border-bottom:1px solid var(--line)}.brand-layout{height:72px;display:flex;gap:24px;align-items:center}.brand{display:flex;align-items:center;flex:none;color:var(--navy);font-weight:800}.brand img{display:block;width:auto;height:auto;max-height:38px;max-width:235px;object-fit:contain}.brand-fallback{font-size:23px;line-height:1.1}.brand-fallback small{display:block;font-size:9px;letter-spacing:.2em}.brand-caption{font-size:13px;margin:0;color:var(--muted)}.brand-caption span{color:#a2b5c2;margin:0 3px}.entry-link{margin-left:auto;display:inline-flex;align-items:center;justify-content:center;background:var(--deep);color:white;border-radius:8px;min-height:42px;padding:0 19px;font-size:14px;font-weight:700;white-space:nowrap}.entry-link:hover{color:#fff;background:#23567a}.desktop-nav{background:var(--navy)}.nav-row{display:grid;grid-template-columns:repeat(7,minmax(0,1fr));gap:6px;align-items:stretch;height:51px}.nav-row a{position:relative;display:flex;align-items:center;justify-content:center;color:#e4eef5;font-size:14px;white-space:nowrap;font-weight:500}.nav-row a[aria-current=page]{color:#fff;font-weight:800}.nav-row a[aria-current=page]:after{content:"";position:absolute;bottom:0;left:32%;right:32%;height:3px;background:var(--teal)}.nav-row a:hover{color:#6ee1eb}.menu-toggle,.mobile-drawer,.mobile-overlay,.no-js-nav,.mobile-quick{display:none}.site-main{min-height:60vh}.section{margin:60px auto}.section-header{max-width:740px;margin-bottom:24px}.eyebrow{font-size:12px;font-weight:800;letter-spacing:.16em;text-transform:uppercase;color:#087b91;margin-bottom:11px}.lead{font-size:18px;color:#4c6476;max-width:840px}.hero{display:grid;grid-template-columns:52fr 48fr;gap:36px;align-items:center;margin-top:50px;margin-bottom:64px}.hero h1{font-size:42px}.hero p{max-width:570px}.hero .lead{font-size:18px}.link-pair{display:flex;gap:12px;flex-wrap:wrap;margin-top:26px}.btn{display:inline-flex;align-items:center;justify-content:center;min-height:45px;padding:8px 20px;border-radius:9px;font-weight:700;font-size:14px;background:var(--navy);color:#fff}.btn:hover{background:#235b7d;color:#fff}.btn.secondary{background:#e4f5f6;color:#075c71}.media-frame{margin:0;display:flex;align-items:center;justify-content:center;width:100%;min-width:0;padding:10px;background:var(--mist);border:1px solid var(--line);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--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-placeholder{min-height:125px;max-width:100%;width:100%;display:flex;align-items:center;justify-content:center;background:repeating-linear-gradient(125deg,#e6eef4,#e6eef4 18px,#edf4f8 18px,#edf4f8 36px);border-radius:9px;color:#8295a3;font-size:13px}.hero .media-placeholder{min-height:225px}.topic-index{border-top:3px solid var(--navy);padding-top:25px}.topic-list{display:grid;grid-template-columns:1fr 1fr;column-gap:38px}.topic-item{padding:20px 0;border-bottom:1px solid var(--line);display:grid;grid-template-columns:38px minmax(0,1fr);gap:12px}.topic-number{font-size:14px;color:#0693a5;font-weight:800}.topic-item h3{margin:0 0 6px;font-size:19px}.topic-item p{margin:0 0 6px;font-size:15px}.topic-item a{font-weight:700;font-size:14px}.focus-layout{display:grid;grid-template-columns:2fr 1fr;gap:22px}.focus-primary{background:var(--navy);padding:36px;border-radius:14px;color:#d8e7f0}.focus-primary h3{font-size:27px;color:#fff}.focus-primary .eyebrow{color:#79dce6}.focus-primary a{color:#8fe6ed}.focus-secondary{display:grid;gap:18px}.focus-secondary article{background:#fff;border:1px solid var(--line);padding:22px;border-radius:12px}.focus-secondary p{font-size:15px}.split-feature{display:grid;grid-template-columns:45fr 55fr;gap:40px;align-items:center}.split-feature.reverse{grid-template-columns:55fr 45fr}.split-feature .feature-text{max-width:670px}.section--tint{background:var(--aqua);padding:42px 0}.section--navy{background:var(--deep);padding:48px 0;color:#dceaf2}.section--navy h2,.section--navy h3{color:#fff}.section--navy a{color:#9ce5ef}.three-notes{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.note{background:#fff;border-left:3px solid var(--teal);padding:24px;border-radius:0 10px 10px 0}.note:nth-child(2){transform:translateY(12px)}.note:nth-child(3){transform:translateY(24px)}.note h3{font-size:18px}.timeline{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;counter-reset:steps}.timeline article{background:white;padding:22px 19px;border-top:3px solid var(--teal);border-radius:7px}.timeline article:before{counter-increment:steps;content:'0' counter(steps);display:block;color:#0f8995;font-weight:800;margin-bottom:12px}.timeline p{font-size:14px}.editor-note{padding:22px 26px;border:1px solid var(--line);background:#fff;border-radius:10px}.page-intro{padding:45px 0 28px;border-bottom:1px solid var(--line);margin-bottom:26px}.page-intro h1{max-width:1000px}.page-intro .lead{margin-bottom:0}.breadcrumb{display:flex;gap:12px;align-items:center;font-size:13px;color:var(--muted);padding-top:24px}.subnav{display:flex;gap:10px;flex-wrap:wrap;padding:13px 0 18px;border-bottom:1px solid var(--line);margin-bottom:30px}.subnav a{padding:5px 15px;background:#e3eef3;border-radius:7px;font-weight:700;font-size:14px}.article-layout{display:grid;grid-template-columns:minmax(0,1fr) 240px;gap:40px;align-items:start}.article-body{min-width:0;max-width:800px}.article-body section{margin-bottom:45px}.article-body p,.prose p{line-height:1.85}.aside-card{background:#fff;border:1px solid var(--line);border-radius:12px;padding:20px;margin-bottom:20px;font-size:14px}.aside-card h3{font-size:17px}.aside-card ul{margin-bottom:0}.table-wrap{overflow-x:auto;max-width:100%;border:1px solid var(--line);border-radius:11px;margin:20px 0 32px;background:#fff}table{border-collapse:collapse;width:100%;min-width:560px;text-align:left;font-size:15px;line-height:1.65}caption{text-align:left;font-weight:700;padding:14px 16px;color:var(--head)}th,td{padding:12px 16px;border-bottom:1px solid var(--line);vertical-align:top}th{background:#eaf1f6;color:#1c4359;font-weight:800}tr:last-child td{border-bottom:0}.steps{counter-reset:serial;padding:0;list-style:none}.steps li{position:relative;padding:7px 0 19px 50px;border-left:2px solid #bcd5df;margin-left:19px}.steps li:before{counter-increment:serial;content:counter(serial);position:absolute;left:-19px;top:3px;border-radius:100%;background:#116b83;color:#fff;width:36px;height:36px;text-align:center;line-height:36px;font-weight:bold}.pullquote{border-left:4px solid var(--teal);background:#e9f8f8;padding:19px 24px;margin:25px 0;font-size:18px;color:#25556b}.comparison-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.comparison-grid article{border:1px solid var(--line);border-top:3px solid var(--teal);border-radius:9px;background:#fff;padding:21px}.comparison-grid h3{font-size:19px}.reading-narrow{max-width:800px}.essay-section{max-width:860px;margin:44px auto}.wide-band{background:#fff;border-block:1px solid var(--line);padding:32px 0}.gallery{display:grid;grid-template-columns:1fr 1fr;gap:26px 36px}.gallery article{min-width:0}.gallery article:nth-child(2){padding-top:36px}.gallery p{font-size:15px}.gallery .media-frame{margin-bottom:16px}.rule-layout{display:grid;grid-template-columns:205px minmax(0,1fr);gap:44px}.rule-toc{position:sticky;top:20px;align-self:start;background:#fff;padding:22px;border-radius:12px;border:1px solid var(--line)}.rule-toc h2{font-size:18px}.rule-toc a{display:block;font-size:14px;padding:6px 0}.rule-layout .article-body{max-width:none}.faq-list{display:grid;gap:9px;margin-top:22px}.faq-item{background:#fff;border:1px solid var(--line);border-radius:9px;padding:0 18px}.faq-item summary{padding:14px 0;cursor:pointer;font-weight:700;color:var(--head)}.faq-item p{padding-bottom:14px;margin:0}.service-layout{display:grid;grid-template-columns:230px minmax(0,1fr);gap:45px}.service-sidebar{background:var(--mist);padding:22px;border-radius:10px;align-self:start}.service-sidebar a{display:block;padding:5px 0}.service-content section{margin:0 0 45px}.related-links{margin:54px auto 68px}.related-links h2{font-size:23px}.related-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.related-grid a{display:flex;justify-content:space-between;gap:14px;align-items:center;background:#fff;border:1px solid var(--line);border-radius:9px;padding:16px 18px;font-weight:700}.related-grid span{color:#09a7b5}.site-footer{background:#0b2539;color:#dcecf5;padding:42px 0 20px;font-size:14px}.site-footer p{max-width:600px}.footer-top{display:flex;justify-content:space-between;gap:45px}.footer-brand{font-size:24px;color:white;font-weight:800}.footer-brand span{font-size:11px;letter-spacing:.1em;margin-left:6px}.footer-top nav{display:grid;grid-template-columns:repeat(2,minmax(110px,1fr));gap:7px 25px;align-content:start}.site-footer a{color:#deedf7}.site-footer a:hover{color:#67dfed}.footer-bottom{border-top:1px solid #285064;margin-top:24px;padding-top:15px;display:flex;justify-content:space-between;gap:20px;color:#b6cbda;font-size:12px}.back-to-top{position:fixed;right:24px;bottom:22px;width:44px;height:44px;border:0;border-radius:50%;background:#12667f;color:#fff;cursor:pointer;box-shadow:0 3px 14px #0003;opacity:0;visibility:hidden;transition:opacity .2s,visibility .2s;z-index:12}.back-to-top.visible{opacity:1;visibility:visible}
@media(max-width:1050px){.container{width:min(calc(100% - 44px),var(--max))}.hero{gap:24px}.hero h1{font-size:37px}.brand-caption{font-size:12px}.section{margin-block:50px}}
@media(max-width:920px){.desktop-nav,.brand-caption{display:none}.brand-layout{height:62px;display:grid;grid-template-columns:40px minmax(0,1fr) auto;gap:10px}.brand{justify-self:center;min-width:0}.brand img{max-height:30px;max-width:min(35vw,175px)}.brand-fallback{font-size:19px}.entry-link{margin-left:0;padding:0 12px;min-height:40px;font-size:12px}.menu-toggle{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;width:40px;height:40px;padding:0;border:1px solid var(--line);border-radius:9px;background:#fff;cursor:pointer}.menu-toggle span{height:2px;width:19px;background:var(--navy)}.mobile-overlay{display:block;position:fixed;inset:0;background:#0b2539a6;opacity:0;visibility:hidden;pointer-events:none;transition:opacity .2s,visibility .2s;z-index:100}.mobile-drawer{display:block;position:fixed;top:0;bottom:0;left:0;width:min(86vw,340px);background:#fff;transform:translateX(-101%);visibility:hidden;pointer-events:none;transition:transform .24s,visibility .24s;z-index:101;overflow-y:auto;box-shadow:5px 0 28px #0002;padding:22px}.menu-open{overflow:hidden}.menu-open .mobile-overlay{opacity:1;visibility:visible;pointer-events:auto}.menu-open .mobile-drawer{transform:translateX(0);visibility:visible;pointer-events:auto}.drawer-header{display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--line);padding-bottom:16px}.drawer-close{font-size:27px;background:none;border:0;width:42px;height:42px;cursor:pointer}.drawer-group{padding:18px 0;border-bottom:1px solid var(--line)}.drawer-group p{margin:0 0 7px;color:var(--muted);font-size:13px;font-weight:700}.drawer-group a{display:block;padding:10px 9px;border-radius:6px;color:var(--head);font-weight:700}.drawer-group a[aria-current=page]{background:var(--aqua);border-left:3px solid var(--teal)}.mobile-quick{display:flex;flex-wrap:wrap;gap:12px 23px;padding:16px 0 22px;font-size:13px}.no-js-nav{display:flex;flex-wrap:wrap;gap:10px;padding:10px 0;background:var(--bg)}.no-js-nav a{font-size:12px}body.js-enabled .no-js-nav{display:none}.article-layout{grid-template-columns:minmax(0,1fr) 200px;gap:25px}.rule-layout{grid-template-columns:180px minmax(0,1fr);gap:25px}}
@media(max-width:760px){.hero,.split-feature,.split-feature.reverse,.focus-layout,.article-layout,.rule-layout,.service-layout{grid-template-columns:1fr}.hero{margin-top:34px}.hero .media-frame{max-width:680px}.article-body{max-width:none}.aside-card{max-width:none}.focus-secondary{grid-template-columns:1fr 1fr}.comparison-grid{grid-template-columns:1fr}.rule-toc{position:static}.service-sidebar{order:2}.service-content{order:1}.three-notes{grid-template-columns:1fr}.note:nth-child(2),.note:nth-child(3){transform:none}.timeline{grid-template-columns:1fr 1fr}.related-grid{grid-template-columns:1fr 1fr}.section--tint,.section--navy{padding:32px 0}.footer-top{flex-direction:column}}
@media(max-width:640px){body{font-size:15px}.container{width:calc(100% - 32px)}h1{font-size:27px}h2{font-size:22px}h3{font-size:18px}.hero h1{font-size:30px}.hero .lead,.lead{font-size:16px}.section{margin-block:38px}.page-intro{padding:32px 0 22px}.topic-list,.gallery,.focus-secondary,.related-grid{grid-template-columns:1fr}.gallery article:nth-child(2){padding-top:0}.focus-primary{padding:26px}.focus-primary h3{font-size:23px}.timeline{grid-template-columns:1fr}.split-feature{gap:22px}.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}.footer-bottom{flex-direction:column;gap:4px}.brand img{max-width:34vw;max-height:29px}.entry-link{padding:0 10px;font-size:12px}.related-links{margin:36px auto}.link-pair .btn{font-size:13px;padding-inline:13px}.media-placeholder{min-height:95px}.hero .media-placeholder{min-height:150px}}
@media(max-width:380px){.brand-layout{gap:5px}.brand img{max-width:33vw}.entry-link{padding:0 8px}.brand-fallback{font-size:16px}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{transition-duration:.01ms!important;animation-duration:.01ms!important}}

.mobile-help-layout{grid-template-columns:minmax(0,1fr) minmax(170px,250px)}@media(max-width:760px){.mobile-help-layout{grid-template-columns:1fr}}