:root{--bg:#F6FAFC;--surface:#fff;--pale:#EAF6FA;--subtle:#EDF4F8;--cyan:#25C8D1;--sky:#25B6E8;--blue:#1787DB;--navy:#174B78;--heading:#183A56;--text:#31485D;--muted:#687D8E;--line:#DCE9F0;--footer:#123653;--radius:16px}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:26px}body{margin:0;background:var(--bg);color:var(--text);font-family:Arial,"PingFang SC","Microsoft YaHei",sans-serif;font-size:16px;line-height:1.8;overflow-wrap:break-word}body.drawer-open{overflow:hidden}img{max-width:100%;height:auto}a{color:var(--navy);text-underline-offset:4px}a:hover{color:var(--blue)}:focus-visible{outline:3px solid var(--cyan);outline-offset:3px}h1,h2,h3,p{margin-top:0}h1,h2,h3{color:var(--heading);line-height:1.38}h1{font-size:clamp(29px,3.2vw,40px);letter-spacing:-.025em}h2{font-size:clamp(23px,2.2vw,27px)}h3{font-size:19px}p{margin-bottom:1.1em}.container{width:min(1180px,calc(100% - 56px));margin-inline:auto}.section{padding:53px 0}.section--white{background:#fff}.section--tint{background:var(--pale)}.section-head{margin-bottom:24px}.section-head h2{margin-bottom:8px}.eyebrow{text-transform:uppercase;font-size:12px;letter-spacing:.17em;font-weight:800;color:#087e99;margin:0 0 9px}.lead{font-size:17px;line-height:1.85;color:#465f73}.muted{color:var(--muted)}.small{font-size:14px}.skip-link{position:absolute;left:10px;top:-100px;background:#fff;padding:8px;z-index:100}.skip-link:focus{top:10px}.site-header{position:relative;z-index:15;background:#fff;border-bottom:1px solid var(--line)}.topbar{height:72px;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{display:inline-flex;align-items:center;text-decoration:none;min-width:140px}.brand-img{display:block;width:auto;height:auto;max-height:38px;max-width:205px;object-fit:contain;object-position:left center}.brand-fallback{font-size:23px;font-weight:900;color:var(--navy);line-height:1.1}.brand-fallback span{display:block;font-size:9px;letter-spacing:.25em}.topbar-tagline{font-size:13px;color:var(--muted);letter-spacing:.14em}.entry-button{display:inline-flex;align-items:center;justify-content:center;min-height:42px;background:var(--navy);color:#fff;text-decoration:none;padding:0 24px;border-radius:9px;font-weight:700;white-space:nowrap}.entry-button:hover{color:#fff;background:#0e6e9a}.desktop-nav{background:var(--navy)}.nav-inner{display:flex;align-items:stretch;justify-content:space-between;gap:10px;min-height:48px}.nav-inner a{display:flex;align-items:center;justify-content:center;position:relative;padding:10px 9px;color:#e6f5ff;text-decoration:none;font-size:14px;white-space:nowrap}.nav-inner a:hover,.nav-inner a.active{color:#fff}.nav-inner a.active{font-weight:800}.nav-inner a.active:after{content:"";position:absolute;bottom:0;left:9px;right:9px;height:3px;background:var(--cyan)}.menu-toggle{display:none}.drawer-overlay,.mobile-drawer,.mobile-bottom{display:none}.home-shortcuts{border-bottom:1px solid var(--line);background:#fff}.shortcuts-inner{display:flex;flex-wrap:wrap;gap:10px 28px;padding-block:13px;font-size:13px}.shortcut-group{display:flex;gap:10px;flex-wrap:wrap}.shortcut-group strong{color:var(--navy)}.shortcut-group a{text-decoration:none;color:var(--muted)}.shortcut-group a:hover{text-decoration:underline;color:var(--blue)}.hero{padding:54px 0 52px;background:linear-gradient(125deg,#F6FAFC,#e8f6fa)}.hero-grid{display:grid;grid-template-columns:minmax(0,56fr) minmax(0,44fr);gap:42px;align-items:center}.hero h1{max-width:640px;margin-bottom:21px}.hero p{max-width:610px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:24px}.button-primary,.button-outline{display:inline-flex;min-height:44px;align-items:center;justify-content:center;padding:9px 19px;border-radius:8px;text-decoration:none;font-weight:750}.button-primary{background:linear-gradient(100deg,#1787DB,#087aaf);color:#fff}.button-primary:hover{color:#fff;filter:brightness(.95)}.button-outline{border:1px solid #9cb9cd;color:var(--navy);background:#fff}.button-outline:hover{border-color:var(--blue)}.media{display:flex;align-items:center;justify-content:center;min-width:0;width:100%;overflow:hidden;background:var(--pale);border-radius:14px}.media img{display:block;width:auto;height:auto;max-width:100%;max-height:100%;object-fit:contain;object-position:center}.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--wide{height:auto;min-height:110px;aspect-ratio:2.6}.media--tall{max-width:300px}.media-placeholder{width:42%;height:45%;border-radius:18px;border:2px solid #d2e8f0;background:linear-gradient(135deg,#e8f7fb,#d8eaf2);position:relative}.media-placeholder:after{content:"";position:absolute;width:34%;height:34%;border:2px solid #b8d7e4;border-radius:50%;left:33%;top:33%}.feature-grid{display:grid;grid-template-columns:minmax(0,2fr) minmax(0,1fr);gap:24px}.editorial-feature{padding:26px;background:#fff;border:1px solid var(--line);border-radius:var(--radius)}.editorial-feature h3{font-size:24px}.feature-side{display:grid;gap:16px}.feature-side article,.topic-card,.info-card{padding:23px;border:1px solid var(--line);background:#fff;border-radius:var(--radius)}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:15px}.topic-card{min-height:170px;display:flex;flex-direction:column}.topic-card .number{font-size:12px;color:#1787DB;font-weight:800}.topic-card h3{margin:9px 0 6px;font-size:18px}.topic-card p{font-size:14px;line-height:1.65;margin-bottom:12px}.topic-card a{margin-top:auto;font-weight:700;text-decoration:underline}.split{display:grid;grid-template-columns:1.05fr 1fr;gap:38px;align-items:center}.split.reverse{grid-template-columns:1fr 1.05fr}.split.reverse>:first-child{order:2}.split.reverse>:last-child{order:1}.clean-list{padding-left:1.3em}.clean-list li{padding-bottom:9px}.triple{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:17px}.info-card h3{margin-bottom:9px}.info-card p{font-size:15px;margin-bottom:0}.reading-path{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px;counter-reset:step}.reading-path article{border-top:3px solid var(--cyan);padding:16px 20px;background:#fff}.reading-path article::before{counter-increment:step;content:"0" counter(step);display:block;font-size:13px;color:#0084a1;font-weight:800}.page-intro{padding:45px 0 32px}.page-intro h1{font-size:clamp(26px,3vw,35px);margin-bottom:18px}.page-intro .lead{max-width:860px}.article-shell{max-width:780px}.article-shell h2{margin-top:30px}.article-shell h3{margin-top:22px}.text-panel{padding:25px;background:#fff;border:1px solid var(--line);border-radius:14px}.section-label{display:flex;gap:10px;align-items:center;color:#00809a;font-size:13px;font-weight:800;letter-spacing:.08em}.section-label::before{content:"";height:3px;width:30px;background:var(--cyan)}.table-wrap{max-width:100%;overflow-x:auto;background:white;border:1px solid var(--line);border-radius:13px}.table-wrap table{width:100%;border-collapse:collapse;min-width:560px;text-align:left}.table-wrap caption{text-align:left;padding:12px 18px;font-weight:700}.table-wrap th,.table-wrap td{padding:15px 18px;vertical-align:top;border-bottom:1px solid var(--line);font-size:15px}.table-wrap th{color:var(--heading);background:#eaf5f9}.table-wrap tr:last-child td{border-bottom:0}.steps{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.step{padding:24px;background:#fff;border-top:4px solid var(--cyan);border-radius:0 0 12px 12px}.step b{color:var(--blue);font-size:14px}.step h3{margin:9px 0}.article-aside{display:grid;grid-template-columns:minmax(0,760px) minmax(0,240px);gap:34px;align-items:start}.aside-box{padding:20px;background:var(--pale);border-radius:14px;position:sticky;top:24px}.aside-box h2{font-size:20px}.aside-box dl{margin:0}.aside-box dt{font-weight:700;color:var(--heading);margin-top:13px}.aside-box dd{margin:0;font-size:14px}.tag-links{display:flex;flex-wrap:wrap;gap:9px}.tag-links a{padding:5px 12px;background:var(--pale);border:1px solid var(--line);border-radius:5px;font-size:14px}.matrix{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.matrix article{background:#fff;border:1px solid var(--line);border-radius:12px;padding:22px}.matrix h3{color:var(--navy)}.gallery-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px}.gallery-grid figure{background:#fff;border:1px solid var(--line);border-radius:14px;padding:17px;margin:0}.gallery-grid figcaption{font-size:15px;padding:13px 3px 2px}.gallery-grid figcaption strong{display:block;color:var(--heading)}.toc{padding:20px 25px;background:#fff;border:1px solid var(--line);border-radius:12px}.toc a{display:inline-block;margin:5px 16px 5px 0}.faq-list{border-top:1px solid var(--line)}.faq-list details{border-bottom:1px solid var(--line);background:#fff}.faq-list summary{cursor:pointer;list-style-position:inside;padding:17px 18px;color:var(--heading);font-weight:700}.faq-list .answer{padding:0 21px 16px 37px}.faq-list p{margin:0}.related{padding:35px 0 55px}.related-links{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.related-links a{padding:17px 20px;background:#fff;border:1px solid var(--line);border-radius:10px;text-decoration:none;display:flex;justify-content:space-between;font-weight:700}.editor-note{background:#e6f4f8;padding:28px;border-left:4px solid var(--cyan);border-radius:4px}.site-footer{background:var(--footer);color:#eaf7ff;padding:48px 0 22px}.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr;gap:60px}.footer-grid p{max-width:390px;font-size:14px;color:#cce3f1}.footer-grid nav{display:flex;flex-direction:column;gap:7px}.footer-grid nav strong{margin-bottom:7px}.site-footer a{color:#eaf7ff;text-decoration:none}.site-footer a:hover{text-decoration:underline}.footer-brand{font-size:22px;font-weight:800}.footer-brand small{display:block;font-size:10px;letter-spacing:.14em}.footer-bottom{border-top:1px solid #345b76;margin-top:30px;padding-top:18px;display:flex;justify-content:space-between;gap:20px;font-size:12px;color:#d6eaf5}.footer-bottom p{max-width:700px}.back-top{position:fixed;bottom:25px;right:20px;border:0;z-index:8;width:42px;height:42px;border-radius:50%;background:var(--navy);color:#fff;cursor:pointer;opacity:0;pointer-events:none;transition:opacity .2s}.back-top.visible{opacity:1;pointer-events:auto}
@media(max-width:980px){.container{width:calc(100% - 44px)}.topbar{height:63px}.menu-toggle{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;width:40px;height:40px;flex-shrink:0;background:none;border:1px solid var(--line);border-radius:8px;cursor:pointer}.menu-toggle span{width:19px;height:2px;background:var(--navy)}.brand{min-width:0;justify-content:center;margin:auto}.brand-img{max-height:30px;max-width:170px}.topbar-tagline,.desktop-nav{display:none}.entry-button{min-height:40px;padding:0 14px;font-size:13px}.drawer-overlay{display:block;position:fixed;inset:0;background:rgba(8,38,58,.52);z-index:18;visibility:hidden;opacity:0;pointer-events:none;transition:opacity .2s,visibility .2s}.mobile-drawer{display:block;position:fixed;top:0;bottom:0;left:0;width:min(86vw,344px);z-index:19;background:white;overflow-y:auto;transform:translateX(-105%);visibility:hidden;pointer-events:none;transition:transform .2s,visibility .2s;box-shadow:8px 0 22px rgba(20,50,80,.08)}.drawer-open .drawer-overlay{visibility:visible;opacity:1;pointer-events:auto}.drawer-open .mobile-drawer{transform:translateX(0);visibility:visible;pointer-events:auto}.drawer-top{display:flex;justify-content:space-between;align-items:center;padding:15px 21px;border-bottom:1px solid var(--line)}.drawer-heading{font-weight:800;font-size:19px;color:var(--heading)}.drawer-close{border:0;background:transparent;color:var(--heading);font-size:31px;width:40px;height:40px;cursor:pointer}.mobile-drawer nav{padding:6px 21px 35px;display:flex;flex-direction:column}.mobile-drawer nav p{font-size:12px;font-weight:800;color:#008eaf;letter-spacing:.09em;margin:18px 0 6px}.mobile-drawer nav a{display:block;padding:9px 10px;text-decoration:none;border-bottom:1px solid var(--line)}.topic-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.article-aside{grid-template-columns:minmax(0,1fr) 210px}.hero-grid{gap:22px}.footer-grid{gap:28px}}
@media(max-width:760px){.container{width:calc(100% - 32px)}.hero{padding:32px 0 38px}.hero-grid,.split,.split.reverse,.feature-grid,.article-aside{grid-template-columns:1fr}.split.reverse>:first-child,.split.reverse>:last-child{order:initial}.hero-grid .media{order:-1}.split{gap:21px}.section{padding:35px 0}.topic-grid,.matrix,.triple,.steps{grid-template-columns:repeat(2,minmax(0,1fr))}.reading-path{grid-template-columns:repeat(2,minmax(0,1fr))}.aside-box{position:static}.footer-grid{grid-template-columns:1fr 1fr}.footer-grid>:first-child{grid-column:1/-1}.footer-bottom{display:block}.related-links{grid-template-columns:1fr}.page-intro{padding:34px 0 22px}}
@media(max-width:640px){body{font-size:15px}.hero h1{font-size:29px}.page-intro h1{font-size:27px}.lead{font-size:16px}.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--banner{height:150px}.media--mobile{height:290px;max-width:250px}.media--wide{height:auto;min-height:80px}.topic-grid,.gallery-grid,.matrix,.triple,.steps{grid-template-columns:1fr}.topic-card{min-height:unset}.reading-path{grid-template-columns:1fr 1fr}.info-card,.topic-card,.editorial-feature,.feature-side article{padding:18px}.shortcuts-inner{gap:7px 12px}.shortcut-group{gap:7px}.brand-img{max-width:130px;max-height:28px}.brand-fallback{font-size:19px}.entry-button{padding:0 10px}.topbar{gap:8px}.footer-grid{grid-template-columns:1fr 1fr;gap:20px}.mobile-bottom{display:grid;grid-template-columns:repeat(4,1fr);position:fixed;bottom:0;left:0;right:0;z-index:10;background:#fff;border-top:1px solid var(--line);padding-bottom:env(safe-area-inset-bottom);box-shadow:0 -4px 18px rgba(20,54,82,.06)}.mobile-bottom a{display:flex;min-height:53px;justify-content:center;align-items:center;text-decoration:none;font-weight:700;font-size:13px}.mobile-bottom a[aria-current]{color:var(--blue);box-shadow:inset 0 3px var(--cyan)}body{padding-bottom:calc(53px + env(safe-area-inset-bottom))}.back-top{bottom:calc(72px + env(safe-area-inset-bottom))}.section-head h2{font-size:22px}.table-wrap table{min-width:530px}}
@media(max-height:520px) and (max-width:640px){.mobile-bottom{position:static}body{padding-bottom:0}.back-top{bottom:20px}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{transition:none!important;animation:none!important}}