:root{--bg:#f4f7fa;--paper:#fff;--mist:#eaf1f6;--aqua:#e9f8f8;--navy:#102e46;--deep:#163c57;--teal:#13b8c5;--blue:#237bd3;--title:#18364b;--ink:#344c60;--muted:#64798a;--line:#dce6ed;--foot:#0b2539}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.8 Arial,'PingFang SC','Microsoft YaHei',sans-serif;overflow-x:hidden}body.drawer-open{overflow:hidden}a{color:#156caa;text-decoration:none}a:hover{text-decoration:underline}img{max-width:100%}button{font:inherit}h1,h2,h3,p,figure{margin-top:0}h1,h2,h3{color:var(--title);line-height:1.35;letter-spacing:-.012em}h1{font-size:clamp(27px,3.1vw,42px)}h2{font-size:clamp(21px,2.3vw,27px)}h3{font-size:19px}p{margin-bottom:1.15em}ul,ol{padding-left:1.4em}.wrap{max-width:1200px;margin:0 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5px}.index-item p{margin:0;font-size:14px}.split-feature{display:grid;grid-template-columns:minmax(0,1.8fr) minmax(240px,1fr);gap:30px}.story-primary{padding:32px;background:var(--navy);color:#dfeef5;border-radius:12px}.story-primary h3,.story-primary h2{color:#fff}.story-stack{display:grid;gap:18px}.mini-story{padding:20px 22px;background:#fff;border-left:4px solid var(--teal);border-radius:5px}.mini-story h3{margin-bottom:8px}.mini-story p{margin-bottom:0}.feature-row{display:grid;grid-template-columns:minmax(0, .95fr) minmax(0,1.05fr);gap:42px;align-items:center}.feature-row.reverse{grid-template-columns:minmax(0,1.2fr) minmax(0,.8fr)}.feature-row>*{min-width:0}.soft-band{padding:36px;background:var(--aqua);border-radius:14px}.rule-cards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;align-items:start}.rule-cards>article{padding:23px;background:#fff;border:1px solid var(--line);border-radius:12px}.rule-cards>article:nth-child(2){margin-top:25px}.rule-cards>article:nth-child(3){margin-top:50px}.pathway{display:grid;grid-template-columns:repeat(4,1fr);gap:0;border-top:1px solid var(--line)}.pathway>div{padding:20px 16px 0 0;min-width:0}.pathway strong{display:block;color:#078e9b;font-size:14px}.pathway h3{font-size:17px;margin:6px 0}.editor-note{background:#e5eef4;padding:26px 30px;border-left:4px solid var(--teal)}.page-intro{padding:45px 0 28px;border-bottom:1px solid var(--line)}.page-intro h1{font-size:clamp(25px,2.8vw,36px);max-width:900px}.page-intro .lead{max-width:850px}.section-kicker{display:block;color:#058a99;font-size:13px;letter-spacing:.08em;font-weight:800;margin-bottom:10px}.section-columns{display:grid;grid-template-columns:minmax(0,1fr) 260px;gap:45px}.side-facts{padding:25px;background:var(--mist);align-self:start;border-radius:12px;font-size:14px}.side-facts h3{font-size:17px}.side-facts li{margin-bottom:10px}.anchor-nav{display:flex;flex-wrap:wrap;gap:10px;margin-top:22px}.anchor-nav a{background:#e6f1f5;border:1px solid #cbdee6;color:var(--deep);border-radius:8px;padding:7px 13px;font-size:14px;font-weight:700}.steps{counter-reset:step;list-style:none;padding:0;display:grid;gap:10px}.steps li{counter-increment:step;padding:18px 20px 18px 64px;position:relative;background:#fff;border:1px solid var(--line);border-radius:9px}.steps li::before{content:counter(step,decimal-leading-zero);position:absolute;left:18px;top:16px;color:#0b929c;font-weight:800}.table-scroll{max-width:100%;overflow-x:auto;border:1px solid var(--line);border-radius:10px;background:#fff}.data-table{width:100%;min-width:590px;border-collapse:collapse;font-size:15px}.data-table caption{text-align:left;font-weight:700;color:var(--title);padding:14px 16px}.data-table th,.data-table td{padding:13px 16px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}.data-table th{background:#eaf1f6;color:var(--title)}.data-table tr:last-child td{border-bottom:0}.chapter{max-width:795px;margin-bottom:38px}.chapter p{line-height:1.85}.pullquote{padding:20px 28px;border-left:4px solid var(--teal);background:#e9f8f8;font-size:18px;color:var(--deep);margin:25px 0}.compact-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:17px}.compact-grid article{padding:23px;background:#fff;border-top:4px solid var(--teal)}.compact-grid article h3{margin-bottom:9px}.compact-grid article p{margin:0}.topic-block{padding:30px 0;border-bottom:1px solid var(--line)}.topic-block:last-child{border-bottom:none}.gallery{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:25px}.gallery article{min-width:0;padding:20px;background:#fff;border-radius:12px}.gallery article:nth-child(2){transform:translateY(20px)}.gallery article h3{margin:20px 0 6px}.gallery article p{font-size:15px}.faq details{background:#fff;border:1px solid var(--line);border-radius:9px;margin:10px 0;padding:0 18px}.faq summary{cursor:pointer;font-weight:700;color:var(--title);padding:13px 0}.faq details p{margin:0 0 18px}.related{border-top:2px solid var(--navy);padding-top:23px}.related-links{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.related-links a{padding:15px 18px;background:#fff;border:1px solid var(--line);border-radius:8px;color:var(--deep);font-weight:700}.help-layout{display:grid;grid-template-columns:235px minmax(0,1fr);gap:38px}.help-aside{background:var(--mist);padding:25px;border-radius:10px;align-self:start}.help-aside a{display:block;padding:8px 0}.site-footer{margin-top:56px;background:var(--foot);color:#dcecf5;font-size:14px}.footer-grid{padding-top:42px;padding-bottom:28px;display:grid;grid-template-columns:2fr 1fr;gap:60px}.footer-brand{font-size:24px;font-weight:800;color:#fff}.footer-brand 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@media(max-width:1024px){.wrap{padding-inline:22px}.feature-row{gap:26px}.section-columns{gap:25px}}
@media(max-width:920px){.brand-inner{height:62px;min-height:62px;display:grid;grid-template-columns:40px minmax(0,1fr) auto;gap:12px;padding-inline:16px}.brand{justify-self:center;min-width:0}.brand img{max-height:30px;max-width:min(37vw,165px)}.brand strong{font-size:20px}.brand-deck,.desktop-nav{display:none}.menu-toggle{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;width:40px;height:40px;border:1px solid #d7e4ed;background:#fff;border-radius:8px;cursor:pointer}.menu-toggle span{width:20px;height:2px;background:var(--navy);border-radius:2px}.entry-link{margin:0;min-height:40px;padding:7px 12px;font-size:13px}.drawer-backdrop.is-visible{position:fixed;inset:0;background:rgba(5,22,35,.52);z-index:29;visibility:visible;pointer-events:auto}.mobile-drawer{position:fixed;inset:0 auto 0 0;width:min(86vw,340px);background:white;z-index:30;transform:translateX(-102%);transition:transform .23s ease;overflow-y:auto;padding:17px 20px;box-shadow:8px 0 28px #102e4626}.mobile-drawer.is-open{visibility:visible;pointer-events:auto;transform:translateX(0)}.drawer-head{display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--line);margin-bottom:16px;padding-bottom:12px}.drawer-close{border:0;background:var(--mist);width:40px;height:40px;border-radius:8px;font-size:25px;cursor:pointer}.drawer-group{font-size:12px;font-weight:700;color:var(--muted);margin:15px 0 4px}.mobile-drawer>a{display:block;padding:10px 12px;color:var(--title);border-radius:8px}.mobile-drawer>a[aria-current]{background:var(--mist);border-left:3px solid var(--teal);font-weight:800}.noscript-nav{display:flex;flex-wrap:wrap;padding:10px 16px;gap:13px;background:var(--mist)}.mobile-shortcuts{display:flex;flex-wrap:wrap;gap:12px;padding-top:20px;font-size:13px}.mobile-shortcuts a{color:var(--deep)}.hero{gap:23px}.section-columns{grid-template-columns:1fr}.side-facts{max-width:650px}}
@media(min-width:921px){.noscript-nav{display:none}}
@media(max-width:760px){.wrap{padding-inline:20px}.hero,.feature-row,.feature-row.reverse,.split-feature,.help-layout{grid-template-columns:1fr}.hero{padding-top:28px}.hero-media{grid-row:2}.compact-grid,.rule-cards,.related-links{grid-template-columns:1fr 1fr}.rule-cards>article:nth-child(n){margin-top:0}.pathway{grid-template-columns:1fr 1fr}.help-layout .help-aside{order:2}.help-layout .help-content{order:1}.gallery article:nth-child(2){transform:none}.footer-grid{gap:25px}}
@media(max-width:640px){body{font-size:15px}.wrap{padding-inline:16px}.content-section{margin-block:36px}.page-intro{padding-top:28px}.lead{font-size:16px}.hero{gap:14px}.media-frame--hero{--media-limit:205px}.media-frame--feature{--media-limit:185px}.media-frame--card{--media-limit:145px}.media-frame--wide{--media-limit:135px}.media-frame--mobile{--media-limit:285px;max-width:250px}.index-lines,.gallery,.compact-grid,.rule-cards,.related-links,.footer-grid{grid-template-columns:1fr}.soft-band{padding:20px}.story-primary{padding:24px}.gallery article{padding:15px}.index-item{padding:16px 0}.pathway{gap:16px}.pathway>div{padding-right:2px}.footer-grid{padding-top:30px}.footer-bottom{flex-direction:column}.anchor-nav a{font-size:13px}.media-frame--hero.media-frame--missing{min-height:130px}.entry-link{padding-inline:10px}}
@media(max-width:360px){.brand-inner{gap:6px;padding-inline:10px}.brand img{max-width:115px}.entry-link{padding-inline:8px;font-size:12px}.wrap{padding-inline:15px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;animation-duration:.01ms!important;transition-duration:.01ms!important}}