:root{--bg:#F6FAFC;--surface:#fff;--soft:#EAF6FA;--soft2:#EDF4F8;--cyan:#25C8D1;--sky:#25B6E8;--blue:#1787DB;--navy:#174B78;--title:#183A56;--body:#31485D;--muted:#687D8E;--line:#DCE9F0;--footer:#123653;--max:1180px}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:30px}body{margin:0;background:var(--bg);color:var(--body);font-family:Arial,'PingFang SC','Microsoft YaHei',sans-serif;line-height:1.8;font-size:16px}body.drawer-open{overflow:hidden}a{color:#126DAD;text-underline-offset:3px}a:hover{color:#06578E}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--cyan);outline-offset:3px}img{max-width:100%;height:auto}h1,h2,h3{color:var(--title);line-height:1.38;margin:0 0 .7em;font-weight:750}h1{font-size:clamp(32px,3vw,40px);letter-spacing:-.02em}h2{font-size:26px}h3{font-size:20px}p{margin:0 0 1.1em}ul,ol{padding-left:1.35em}li+li{margin-top:.45em}table{border-collapse:collapse;width:100%;line-height:1.65;text-align:left;font-size:15px}th,td{border-bottom:1px solid var(--line);padding:13px 15px;vertical-align:top}th{background:#EAF6FA;color:var(--title);font-weight:700}tbody tr:nth-child(even){background:#F8FBFD}.table-scroll{width:100%;overflow-x:auto;border:1px solid var(--line);border-radius:13px}.container{width:min(calc(100% - 56px),var(--max));margin-inline:auto}.skip-link{position:absolute;top:-100px;left:10px;z-index:100;background:white;padding:10px}.skip-link:focus{top:10px}.site-header{background:white;border-bottom:1px solid var(--line);position:relative;z-index:15}.top-bar{height:72px;display:flex;align-items:center;gap:24px}.brand{display:flex;align-items:center;color:var(--title);font-size:23px;text-decoration:none;max-width:260px;min-width:0;flex-shrink:0}.brand img{display:block;width:auto;height:auto;max-height:38px;max-width:245px;object-fit:contain;object-position:left center}.brand-descriptor{margin-left:auto;color:var(--muted);letter-spacing:.08em;font-size:14px}.entry-button,.button-primary{background:linear-gradient(105deg,#1787DB,#159AB5);color:#fff;text-decoration:none;border-radius:9px;font-weight:700;padding:9px 23px;display:inline-flex;align-items:center;justify-content:center;min-height:42px;white-space:nowrap}.entry-button:hover,.button-primary:hover{color:#fff;background:#174B78}.desktop-nav{background:var(--navy)}.nav-inner{min-height:48px;display:flex;align-items:stretch;justify-content:space-between;gap:5px}.desktop-nav a{display:flex;align-items:center;padding:9px 15px 7px;color:#ECFAFF;text-decoration:none;font-size:15px;border-bottom:3px solid transparent;white-space:nowrap}.desktop-nav a:hover,.desktop-nav a[aria-current=page]{color:#fff;background:#22618C;border-bottom-color:#59E1E9}.menu-button{display:none;width:40px;height:40px;border:1px solid var(--line);border-radius:8px;background:#fff;padding:9px;cursor:pointer;flex-direction:column;justify-content:space-around}.menu-button span{display:block;background:var(--title);height:2px;width:100%}.drawer-overlay{visibility:hidden;pointer-events:none;position:fixed;inset:0;background:rgba(13,34,52,.54);opacity:0;z-index:30;transition:opacity .2s,visibility .2s}.mobile-drawer{visibility:hidden;position:fixed;z-index:31;top:0;bottom:0;left:0;width:min(86vw,344px);max-width:100%;overflow:auto;background:#fff;transform:translateX(-101%);transition:transform .2s,visibility .2s;box-shadow:10px 0 30px #163D5520;padding:22px}.drawer-open .drawer-overlay{visibility:visible;pointer-events:auto;opacity:1}.drawer-open .mobile-drawer{visibility:visible;transform:translateX(0)}.drawer-head{display:flex;align-items:center;justify-content:space-between;color:var(--title);font-size:20px;margin-bottom:18px}.drawer-close{border:1px solid var(--line);background:var(--soft);color:var(--title);border-radius:8px;width:40px;height:40px;font-size:26px;cursor:pointer}.drawer-section{display:flex;flex-direction:column;gap:4px;padding:14px 0;border-top:1px solid var(--line)}.drawer-section>span{font-size:13px;color:var(--muted);font-weight:700}.drawer-section a{text-decoration:none;padding:8px 10px;color:var(--title);font-weight:600;border-radius:6px}.drawer-section a:hover{background:var(--soft)}.shortcut-bar{background:#ECF6FA;border-bottom:1px solid var(--line)}.shortcut-inner{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px;padding:13px 0}.shortcut-inner>div{display:flex;align-items:center;gap:10px;flex-wrap:wrap;font-size:13px}.shortcut-inner b{color:var(--navy)}.shortcut-inner a{font-size:13px}.main-content{min-height:60vh}.hero{display:grid;grid-template-columns:1.12fr .88fr;gap:42px;align-items:center;padding:48px 0 26px}.eyebrow{color:#147A96;font-size:13px;letter-spacing:.12em;text-transform:uppercase;font-weight:700;margin-bottom:12px}.hero h1{margin-bottom:19px}.hero p{font-size:16.5px;max-width:650px}.hero-actions{display:flex;flex-wrap:wrap;gap:12px;margin-top:23px}.button-outline{display:inline-flex;padding:8px 20px;min-height:42px;border:1px solid #A7C9DA;border-radius:9px;text-decoration:none;color:var(--navy);font-weight:700;align-items:center}.button-outline:hover{background:var(--soft)}.media{width:100%;min-width:0;display:flex;align-items:center;justify-content:center;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-placeholder{display:block;width:60%;height:55%;border-radius:15px;border:2px dashed #C7E1E9;background:linear-gradient(115deg,#EAF6FA,#F4FAFD)}.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:300px;margin-inline:auto}.media--wide{height:180px}.content-section{margin:54px 0}.content-section h2{position:relative}.section-lead{max-width:820px;color:var(--muted);margin-bottom:23px}.panel{background:white;border:1px solid var(--line);border-radius:16px;padding:26px}.panel-soft{background:var(--soft);border-radius:16px;padding:28px}.section-header{display:flex;align-items:end;justify-content:space-between;gap:15px}.section-header a{white-space:nowrap}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.topic-card{padding:21px;background:#fff;border:1px solid var(--line);border-radius:13px;text-decoration:none;transition:border-color .15s,transform .15s}.topic-card:hover{border-color:#83C9DD;transform:translateY(-2px)}.topic-card h3{font-size:18px;margin-bottom:9px}.topic-card p{font-size:14px;color:var(--body);line-height:1.7;margin:0}.editorial-grid{display:grid;grid-template-columns:2fr 1fr;gap:20px}.editorial-primary{padding:32px;background:var(--navy);color:#ECF9FC;border-radius:16px}.editorial-primary h3{color:#fff;font-size:24px}.editorial-primary a{color:#C7F7FE}.editorial-stack{display:grid;gap:18px}.editorial-stack article{background:white;border:1px solid var(--line);border-radius:14px;padding:22px}.editorial-stack h3{font-size:19px}.feature-row{display:grid;grid-template-columns:1fr 1fr;align-items:center;gap:35px}.feature-row--reverse .feature-copy{order:2}.feature-row--reverse .feature-media{order:1}.feature-copy{min-width:0}.feature-media{min-width:0}.mini-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.mini-grid article{background:#fff;border:1px solid var(--line);border-radius:13px;padding:23px}.mini-grid h3{font-size:18px}.steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:18px;counter-reset:step}.steps>div{border-top:3px solid var(--cyan);padding-top:13px}.steps strong{display:block;color:var(--title)}.steps span{display:block;color:var(--muted);font-size:14px}.page-intro{padding:42px 0 22px;max-width:910px}.page-intro h1{font-size:35px}.page-intro .lede{font-size:17px;color:var(--body)}.article-width{max-width:780px}.article-layout{display:grid;grid-template-columns:minmax(0,760px) minmax(180px,240px);gap:52px;align-items:start}.article-layout aside{position:sticky;top:22px}.aside-card{border-left:3px solid var(--cyan);padding:16px;background:#EAF6FA;border-radius:4px 12px 12px 4px}.aside-card h2{font-size:19px}.definition-list{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.definition-list article{background:white;border:1px solid var(--line);border-radius:12px;padding:20px}.definition-list h3{font-size:18px}.compare-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.compare-grid article{background:white;border-top:4px solid var(--blue);border-radius:12px;padding:23px}.compare-grid article:nth-child(2){border-color:var(--cyan)}.compare-grid article:nth-child(3){border-color:#58A7BB}.keyline{border-left:4px solid var(--cyan);padding:12px 0 12px 23px;margin:22px 0;background:linear-gradient(90deg,var(--soft),transparent)}.gallery-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.gallery-grid figure{background:white;border:1px solid var(--line);padding:17px;margin:0;border-radius:14px}.gallery-grid figcaption{padding:12px 3px 2px;color:var(--body);font-size:14px}.gallery-grid figcaption strong{display:block;color:var(--title);font-size:17px}.reading-index{background:#EAF6FA;border:1px solid #D3E9EF;border-radius:14px;padding:22px}.reading-index h2{font-size:20px;margin:0 0 10px}.reading-index ul{margin:0}.reading-index a{font-weight:650}.related-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.related-card{display:flex;flex-direction:column;gap:8px;text-decoration:none;background:#fff;border:1px solid var(--line);border-radius:13px;padding:22px}.related-card strong{color:var(--title);font-size:18px}.related-card span{font-size:14px;color:var(--body)}.related-card .related-more{margin-top:auto;padding-top:10px;color:#126DAD;font-weight:700}details{border-bottom:1px solid var(--line);padding:15px 5px}details summary{cursor:pointer;font-weight:700;color:var(--title)}details p{margin:10px 0 0}details[open] summary{color:#126DAD}.faq-list{background:white;border:1px solid var(--line);padding:10px 23px;border-radius:14px}.note{font-size:14px;color:var(--muted)}.notice-box{padding:22px 24px;background:#EAF6FA;border-left:4px solid var(--sky);border-radius:5px 13px 13px 5px}.site-footer{background:var(--footer);color:#EAF7FF;margin-top:72px;padding:46px 0 20px;font-size:14px}.footer-grid{display:grid;grid-template-columns:2.1fr 1fr 1fr;gap:60px}.footer-brand{font-size:24px;font-weight:750;color:#fff}.footer-brand small{font-size:12px;margin-left:10px;letter-spacing:.08em}.site-footer h2{font-size:16px;color:#fff}.site-footer nav a{display:block;color:#D7F6FF;margin:5px 0;text-decoration:none}.site-footer nav a:hover{text-decoration:underline}.footer-bottom{border-top:1px solid #ffffff26;padding-top:16px;display:flex;justify-content:space-between;gap:10px;margin-top:30px;color:#CBE4F2}.mobile-bottom-nav{display:none}.back-to-top{visibility:hidden;opacity:0;position:fixed;right:22px;bottom:20px;z-index:18;border:0;border-radius:50%;width:44px;height:44px;background:var(--navy);color:white;font-size:22px;cursor:pointer;transition:opacity .2s}.back-to-top.is-visible{visibility:visible;opacity:1}.two-column{display:grid;grid-template-columns:1fr 1fr;gap:20px}.compact-list li{margin-bottom:8px}.quiet-band{border-top:1px solid var(--line);padding-top:24px;color:var(--muted);font-size:14px}
@media(max-width:980px){.container{width:min(calc(100% - 44px),var(--max))}.top-bar{height:64px;gap:12px;justify-content:space-between}.menu-button{display:flex}.brand{margin-right:auto;max-width:220px}.brand img{max-height:30px;max-width:190px}.brand-descriptor,.desktop-nav{display:none}.entry-button{min-height:40px;padding:7px 16px}.shortcut-inner{grid-template-columns:1fr;gap:6px}.hero{gap:26px}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.article-layout{grid-template-columns:minmax(0,1fr)}.article-layout aside{position:static}.footer-grid{gap:30px}}
@media(max-width:760px){.hero,.feature-row,.editorial-grid,.two-column{grid-template-columns:1fr}.hero{padding:32px 0 10px}.feature-row--reverse .feature-copy,.feature-row--reverse .feature-media{order:initial}.mini-grid,.compare-grid,.related-grid,.steps{grid-template-columns:1fr 1fr}.gallery-grid{grid-template-columns:1fr}.footer-grid{grid-template-columns:1fr 1fr}.footer-grid>div:first-child{grid-column:1/-1}.page-intro{padding:32px 0 10px}.content-section{margin:38px 0}}
@media(max-width:640px){body{font-size:15px;line-height:1.78}.container{width:calc(100% - 32px)}h1{font-size:29px}h2{font-size:22px}h3{font-size:18px}.page-intro h1{font-size:27px}.page-intro .lede{font-size:15.5px}.hero h1{font-size:29px}.hero p{font-size:15.5px}.brand{max-width:160px;font-size:18px}.brand img{max-width:155px;max-height:28px}.entry-button{padding:6px 11px;font-size:13px;min-height:38px}.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--banner,.media--wide{height:150px}.media--mobile{height:290px;max-width:250px}.topic-grid,.mini-grid,.compare-grid,.related-grid,.steps,.definition-list{grid-template-columns:1fr}.topic-card,.panel,.panel-soft{padding:18px}.editorial-primary{padding:23px}.section-header{display:block}.section-header a{display:inline-block;margin:0 0 14px}.shortcut-inner>div{gap:7px}.footer-grid{grid-template-columns:1fr}.footer-grid>div:first-child{grid-column:auto}.footer-bottom{flex-direction:column}.site-footer{padding-bottom:90px;margin-top:45px}.mobile-bottom-nav{display:grid;grid-template-columns:repeat(4,1fr);position:fixed;bottom:0;left:0;right:0;z-index:19;padding:5px 0 calc(5px + env(safe-area-inset-bottom));background:#fff;border-top:1px solid var(--line);box-shadow:0 -3px 12px #12365310}.mobile-bottom-nav a{text-align:center;padding:8px 3px;text-decoration:none;font-size:13px;color:var(--title)}.mobile-bottom-nav a[aria-current=page]{color:#087A9A;font-weight:700;border-top:2px solid var(--cyan)}.back-to-top{right:13px;bottom:80px;width:40px;height:40px}.table-scroll table{min-width:570px}th,td{padding:11px}.site-footer p{max-width:570px}}
@media(max-width:360px){.brand{max-width:125px}.brand img{max-width:120px}.top-bar{gap:8px}.entry-button{padding:6px 9px}}
@media(max-height:480px) and (max-width:640px){.mobile-bottom-nav{position:static}.site-footer{padding-bottom:25px}.back-to-top{bottom:15px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{transition:none!important;animation:none!important}}