:root{--page:#F6FAFC;--surface:#fff;--tint:#EAF6FA;--soft:#EDF4F8;--cyan:#25C8D1;--sky:#25B6E8;--blue:#1787DB;--navy:#174B78;--heading:#183A56;--body:#31485D;--muted:#687D8E;--border:#DCE9F0;--footer:#123653;--container:1180px}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:36px}body{margin:0;background:var(--page);color:var(--body);font:16px/1.8 Arial,"PingFang SC","Microsoft YaHei",sans-serif;overflow-x:hidden}a{color:var(--navy);text-decoration-thickness:1px;text-underline-offset:4px}a:hover{color:#0876b8}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid #1787DB;outline-offset:3px}img{max-width:100%;height:auto}button{font:inherit;cursor:pointer}h1,h2,h3,h4{color:var(--heading);line-height:1.36;letter-spacing:-.02em}h1{font-size:clamp(27px,4.2vw,42px);margin:12px 0 18px}h2{font-size:clamp(21px,2.65vw,27px);margin:0 0 18px}h3{font-size:clamp(17px,2vw,21px);margin:0 0 12px}p{margin:0 0 17px}.container{max-width:var(--container);margin:auto;padding-left:28px;padding-right:28px}.skip-link{position:absolute;left:10px;top:-100px;background:#fff;padding:8px;z-index:110}.skip-link:focus{top:10px}.site-header{background:var(--surface);border-bottom:1px solid var(--border);position:relative;z-index:20}.topbar{height:72px;display:flex;align-items:center;gap:20px}.site-brand{display:flex;align-items:center;text-decoration:none;min-width:0}.site-brand img{display:block;width:auto;max-height:38px;max-width:230px;object-fit:contain}.brand-fallback{font-size:22px;font-weight:800;color:var(--navy);line-height:1.2}.brand-fallback small{display:block;font-size:10px;letter-spacing:.13em}.brand-promise{margin:0 auto;color:var(--muted);font-size:14px}.entry-button{display:inline-flex;align-items:center;justify-content:center;gap:12px;flex:none;padding:9px 24px;background:linear-gradient(115deg,#1787DB,#139DB9);color:#fff;border-radius:9px;font-size:14px;font-weight:700;text-decoration:none;min-height:42px}.entry-button:hover{background:#174B78;color:#fff}.desktop-nav{background:var(--navy)}.nav-track{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:48px}.nav-track a{display:flex;align-items:center;justify-content:center;white-space:nowrap;text-decoration:none;color:#e9f6ff;padding:10px 4px;border-bottom:3px solid transparent;font-size:14px}.nav-track a:hover,.nav-track a[aria-current]{border-bottom-color:var(--cyan);color:#fff}.menu-toggle{display:none}.mobile-menu,.menu-overlay,.mobile-bottom{display:none}.section{padding:56px 0}.section--white{background:#fff}.section--tint{background:var(--tint)}.section-heading{max-width:760px;margin-bottom:25px}.section-heading .overline,.eyebrow{display:inline-block;color:#1475a2;font-weight:800;letter-spacing:.12em;text-transform:uppercase;font-size:12px}.section-heading p{color:var(--muted)}.hero{padding:46px 0 50px;background:linear-gradient(125deg,#f5fbfd,#e9f7fb 70%,#eef8fc)}.hero-grid{display:grid;grid-template-columns:minmax(0,1.12fr) minmax(0,.88fr);align-items:center;gap:46px}.hero-copy .lead{font-size:17px;color:#466276;max-width:620px}.hero-actions{display:flex;flex-wrap:wrap;gap:12px;margin-top:24px}.button-primary,.button-outline{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:10px 20px;border-radius:9px;font-weight:700;text-decoration:none;font-size:14px}.button-primary{background:var(--navy);color:#fff}.button-primary:hover{background:#126ba1;color:#fff}.button-outline{border:1px solid #8bb9d1;background:#fff}.quicklinks{background:#fff;border-bottom:1px solid var(--border)}.quicklinks-inner{display:flex;gap:25px;flex-wrap:wrap;padding-top:13px;padding-bottom:13px}.quicklinks p{margin:0;font-size:13px}.quicklinks strong{color:var(--heading)}.quicklinks a{margin-left:8px}.media{margin:0;display:flex;align-items:center;justify-content:center;min-width:0;width:100%;overflow:hidden;border-radius:14px;background:#eaf6fa}.media img{display:block;width:auto;height:auto;max-width:100%;max-height:100%;object-fit:contain;object-position:center}.media-placeholder{width:90%;height:78%;max-height:100%;border-radius:8px;background:linear-gradient(140deg,#e2f0f6,#d2e7ef);opacity:.76}.media--hero{height:clamp(250px,26vw,330px)}.media--feature{height:250px}.media--card{height:170px}.media--banner{height:220px}.media--mobile{height:350px;max-width:320px}.media--portrait{max-width:340px;margin-inline:auto}.media--wide{background:#f1f8fb}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.topic-item{position:relative;padding:22px;background:#fff;border:1px solid var(--border);border-top:3px solid var(--cyan);border-radius:12px;text-decoration:none;transition:transform .2s,border-color .2s;min-width:0}.topic-item:hover{transform:translateY(-2px);border-color:#79bdcf}.topic-item strong{display:block;font-size:17px;color:var(--heading);margin-bottom:9px}.topic-item span{display:block;font-size:14px;line-height:1.75;color:var(--muted)}.editor-grid{display:grid;grid-template-columns:2fr 1fr;gap:20px}.editor-feature{background:var(--navy);color:#e6f5ff;padding:32px;border-radius:14px}.editor-feature h3{font-size:25px;color:#fff}.editor-feature p{color:#d9ebf5}.editor-feature a{color:#fff}.editor-side{display:grid;gap:20px}.editor-mini{padding:22px;background:var(--soft);border-radius:12px}.feature-split{display:grid;grid-template-columns:1.1fr .9fr;align-items:center;gap:38px}.feature-split.reverse{grid-template-columns:.9fr 1.1fr}.feature-split.reverse .media{order:-1}.text-link{font-weight:700}.triad{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.knowledge-card{padding:24px;border:1px solid var(--border);border-radius:12px;background:#fff}.knowledge-number{font-size:12px;letter-spacing:.1em;color:#137fa2;font-weight:800;display:block;margin-bottom:10px}.steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px;counter-reset:path}.steps>div{border-top:2px solid var(--cyan);padding-top:15px}.steps strong{display:block;color:var(--heading)}.steps span{font-size:14px;color:var(--muted)}.editor-note{padding:19px 22px;border-left:4px solid var(--cyan);background:#fff;font-size:14px;color:var(--muted)}.page-intro{padding-top:44px;padding-bottom:30px}.page-intro h1{font-size:clamp(25px,3vw,36px);max-width:910px}.page-intro .lead{max-width:850px;font-size:17px;color:#52697b}.article-layout{padding-bottom:50px}.article-layout section,.article-layout article{scroll-margin-top:30px}.article-section{margin:0 0 42px}.article-section>p{max-width:830px}.article-prose{max-width:780px}.article-prose p{margin-bottom:18px}.article-prose h2{margin-top:38px}.article-prose h3{margin-top:25px}.content-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:24px;align-items:start}.surface-panel{padding:25px;background:#fff;border:1px solid var(--border);border-radius:12px}.panel-soft{background:var(--soft);border:0}.timeline{display:grid;gap:0;counter-reset:timeline}.timeline>div{border-left:2px solid var(--cyan);padding:0 0 25px 25px;position:relative}.timeline>div:before{content:'';position:absolute;left:-7px;top:6px;width:12px;height:12px;background:var(--cyan);border-radius:50%;border:2px solid #fff}.timeline strong{color:var(--heading);display:block;margin-bottom:4px}.timeline p{margin-bottom:0}.table-scroll{overflow-x:auto;margin:18px 0 26px;border:1px solid var(--border);border-radius:10px;background:#fff}.data-table{width:100%;border-collapse:collapse;min-width:540px;text-align:left}.data-table th,.data-table td{padding:14px 17px;border-bottom:1px solid var(--border);vertical-align:top}.data-table th{background:var(--navy);color:#fff;font-size:14px}.data-table td:first-child{font-weight:700;color:var(--heading)}.data-table tr:last-child td{border-bottom:0}.tag-list{display:flex;gap:10px;flex-wrap:wrap;margin:18px 0}.tag-list a,.tag-list span{background:#e5f3f9;border:1px solid #cde6f1;padding:5px 12px;border-radius:6px;text-decoration:none;font-size:14px}.article-aside-layout{display:grid;grid-template-columns:minmax(0,760px) minmax(0,240px);gap:50px;align-items:start}.glossary{background:#eaf6fa;padding:22px;border-radius:12px}.glossary h2{font-size:20px}.glossary dl{margin:0}.glossary dt{font-weight:700;color:var(--heading);margin-top:15px}.glossary dd{margin:0;font-size:14px;color:var(--body)}.guide-matrix{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.guide-matrix .surface-panel{height:100%}.gallery-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px}.gallery-tile{background:#fff;padding:18px;border:1px solid var(--border);border-radius:12px}.gallery-tile figcaption{padding:13px 4px 2px;color:var(--body);font-size:14px}.gallery-tile strong{color:var(--heading);display:block;font-size:17px}.chapter-index{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:30px}.chapter-index a{padding:8px 15px;background:#fff;border:1px solid var(--border);border-radius:8px;text-decoration:none;font-weight:700}.faq-list{display:grid;gap:10px}.faq-list details{background:#fff;border:1px solid var(--border);border-radius:10px;padding:0 20px}.faq-list summary{font-weight:700;color:var(--heading);cursor:pointer;padding:14px 0}.faq-list details p{padding:0 0 14px;margin:0}.related{padding:35px 0 8px;border-top:1px solid var(--border);margin-top:45px}.related-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.related-link{background:#fff;padding:20px;border:1px solid var(--border);border-radius:10px;text-decoration:none;display:flex;flex-direction:column;gap:9px}.related-link strong{color:var(--heading)}.related-link span{font-size:14px;color:var(--muted)}.related-link span:last-child{text-align:right;font-size:19px;color:var(--blue)}.site-footer{background:var(--footer);color:#eaf7ff;padding:44px 0 18px}.footer-layout{display:grid;grid-template-columns:1.25fr 1fr;gap:60px}.footer-brand{font-size:22px}.footer-brand span{display:block;font-size:11px;letter-spacing:.13em}.footer-layout p{color:#c9deea;font-size:14px;max-width:470px}.footer-layout nav strong{display:block;margin-bottom:13px}.footer-links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px 16px}.footer-links a{color:#d6e9f4;font-size:14px;text-decoration:none}.footer-links a:hover{text-decoration:underline}.footer-bottom{display:flex;justify-content:space-between;gap:16px;border-top:1px solid #3b617d;margin-top:26px;padding-top:16px;font-size:12px;color:#c2d8e5}.back-top{position:fixed;right:22px;bottom:24px;width:42px;height:42px;border:0;border-radius:50%;background:var(--navy);color:#fff;font-size:23px;opacity:0;visibility:hidden;pointer-events:none;transition:opacity .2s;z-index:15}.back-top.is-visible{opacity:1;visibility:visible;pointer-events:auto}
@media(max-width:980px){.container{padding-left:22px;padding-right:22px}.topbar{height:64px;justify-content:space-between;gap:10px}.menu-toggle{width:40px;height:40px;flex:none;display:flex;flex-direction:column;justify-content:center;align-items:center;gap:5px;background:#fff;border:1px solid var(--border);border-radius:8px}.menu-toggle span{width:18px;height:2px;background:var(--navy)}.site-brand{margin:0 auto}.site-brand img{max-height:30px;max-width:175px}.brand-fallback{font-size:17px}.brand-fallback small{font-size:8px}.brand-promise,.desktop-nav{display:none}.entry-button{padding:6px 11px;font-size:12px;min-height:40px;white-space:nowrap;gap:4px}.menu-overlay{display:block;position:fixed;inset:0;background:rgba(10,32,50,.46);z-index:50;opacity:0;visibility:hidden;pointer-events:none;transition:opacity .2s,visibility .2s}.mobile-menu{display:flex;flex-direction:column;position:fixed;top:0;bottom:0;left:0;width:min(86vw,344px);background:#fff;z-index:51;box-shadow:6px 0 35px #12365325;padding:17px 22px 30px;overflow-y:auto;transform:translateX(-105%);visibility:hidden;pointer-events:none;transition:transform .2s,visibility .2s}.mobile-menu a{font-weight:700;padding:9px 8px;border-bottom:1px solid var(--border);text-decoration:none;color:var(--heading)}.drawer-head{display:flex;justify-content:space-between;align-items:center;font-size:19px;color:var(--heading)}.drawer-close{background:transparent;border:0;color:var(--heading);font-size:30px;line-height:1;padding:7px}.drawer-label{font-size:12px;color:var(--muted);font-weight:700;margin:22px 0 0}.menu-open{overflow:hidden}.menu-open .menu-overlay{opacity:1;visibility:visible;pointer-events:auto}.menu-open .mobile-menu{visibility:visible;pointer-events:auto;transform:translateX(0)}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.article-aside-layout{grid-template-columns:minmax(0,1fr) 220px;gap:24px}}
@media(max-width:760px){.section{padding:38px 0}.hero{padding:32px 0}.hero-grid,.feature-split,.feature-split.reverse,.editor-grid,.content-grid,.article-aside-layout,.footer-layout{grid-template-columns:1fr;gap:24px}.hero-grid .media{order:1}.feature-split.reverse .media{order:0}.triad,.guide-matrix{grid-template-columns:1fr}.steps{grid-template-columns:repeat(2,minmax(0,1fr))}.article-aside-layout .glossary{margin-top:0}.related-grid{grid-template-columns:1fr}.site-footer{padding-bottom:90px}.footer-bottom{flex-wrap:wrap}.quicklinks-inner{gap:5px 18px}.quicklinks p{width:100%}.page-intro{padding-top:32px}.article-section{margin-bottom:32px}}
@media(max-width:640px){body{font-size:15px;line-height:1.78}.container{padding-left:16px;padding-right:16px}h1{font-size:clamp(27px,7vw,31px)}h2{font-size:21px}h3{font-size:18px}.hero-copy .lead,.page-intro .lead{font-size:15px}.topbar{height:62px}.site-brand img{max-height:28px;max-width:145px}.brand-fallback{font-size:15px}.entry-button{min-height:38px;padding:6px 9px;font-size:12px}.entry-button span{display:none}.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--banner{height:150px}.media--mobile{height:290px;max-width:250px}.media--portrait{max-width:250px}.topic-grid,.gallery-grid{grid-template-columns:1fr}.topic-item{padding:18px}.section-heading{margin-bottom:16px}.editor-feature{padding:24px}.editor-feature h3{font-size:21px}.surface-panel,.knowledge-card{padding:18px}.steps{gap:12px}.mobile-bottom{position:fixed;bottom:0;left:0;right:0;z-index:18;display:grid;grid-template-columns:repeat(4,1fr);background:#fff;border-top:1px solid var(--border);padding-bottom:env(safe-area-inset-bottom,0px);box-shadow:0 -4px 15px #174B7810}.mobile-bottom a{text-align:center;text-decoration:none;font-weight:700;font-size:13px;color:var(--heading);padding:10px 2px;min-height:46px}.mobile-bottom a[aria-current]{color:var(--blue);box-shadow:inset 0 3px var(--cyan)}.back-top{bottom:72px;right:13px}.site-footer{padding-bottom:90px}.gallery-tile{padding:12px}.faq-list details{padding:0 14px}}
@media(max-width:640px) and (max-height:530px){.mobile-bottom{position:static;padding-bottom:0}.site-footer{padding-bottom:24px}.back-top{bottom:18px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{transition-duration:.01ms!important;animation-duration:.01ms!important}}