*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:#F5F8FA;color:#294356;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;font-size:16px;line-height:1.75}a{color:#176A91;text-decoration:none}a:hover{text-decoration:underline}a:focus-visible,button:focus-visible{outline:3px solid #D1A35B;outline-offset:3px}img{display:block;max-width:100%;width:auto;height:auto;object-fit:contain;object-position:center center}button{font:inherit;cursor:pointer}.container{max-width:1120px;margin:auto;padding:0 24px}.readable{max-width:760px}.skip{position:absolute;top:-100px;left:16px;background:#fff;padding:8px;z-index:20}.skip:focus{top:8px}.site-header{background:#fff;border-bottom:1px solid #DCE6EC;position:relative;z-index:5}.nav-shell{max-width:1120px;margin:auto;padding:0 24px;min-height:72px;display:flex;align-items:center;gap:25px}.brand{display:flex;align-items:center;gap:9px;flex-shrink:0;color:#173044;font-size:21px;font-weight:800;line-height:1.1}.brand small{display:block;letter-spacing:.15em;font-size:10px;color:#607789;margin-top:3px}.brand-logo{max-width:140px;max-height:34px}.primary,.header-right{display:flex;align-items:center;gap:19px}.primary{flex:1;justify-content:center}.primary a,.header-right a{font-size:14px;white-space:nowrap;color:#294356}.primary a[aria-current=page],.topic-inner a[aria-current=page]{color:#176A91;border-bottom:2px solid #D1A35B}.header-right{gap:15px}.topic-strip{background:#EAF3F7}.topic-inner{max-width:1120px;margin:auto;display:flex;gap:34px;align-items:center;padding:6px 24px;min-height:40px}.topic-inner a{font-size:14px;color:#294356}.mobile-menu-button,.mobile-dir,.mobile-categories,.bottom-nav{display:none}.footer{background:#123247;color:#e7f0f5;margin-top:64px}.footer-inner{max-width:1120px;margin:auto;padding:42px 24px 15px}.footer-lead{display:grid;grid-template-columns:230px 1fr;gap:30px;border-bottom:1px solid #385465;padding-bottom:25px}.footer-lead strong{font-size:21px}.footer-lead strong span{font-size:11px;letter-spacing:.18em}.footer-lead p{max-width:750px;margin:0;font-size:14px}.footer-logo{max-width:130px;max-height:30px;margin-top:10px}.footer-links{display:grid;grid-template-columns:repeat(4,1fr);gap:22px;padding:22px 0}.footer-links h2{font-size:16px;color:#fff;margin:0 0 12px}.footer-links a{color:#d4e5ef;display:block;font-size:13px;margin:4px 0}.copyright{border-top:1px solid #385465;padding:16px 0;font-size:13px;color:#c4d9e5}.page-hero{background:linear-gradient(112deg,#EAF3F7,#fff);border-bottom:1px solid #DCE6EC;padding:44px 0}.eyebrow{font-size:13px;font-weight:700;color:#176A91;letter-spacing:.06em}.page-hero h1,.hero h1{color:#173044;font-size:30px;line-height:1.3;margin:13px 0 15px}.page-hero p{max-width:760px;margin:0}.breadcrumbs{font-size:13px;color:#607789}.page-body{padding-top:34px}.article-section{margin:0 0 32px;padding:22px 24px;background:white;border:1px solid #DCE6EC;border-radius:12px;box-shadow:0 3px 14px #17304408}.article-section h2{margin:0 0 13px;font-size:23px;color:#173044}.article-section p{margin:10px 0}.tip{background:#F7F1E6;padding:14px 18px;border-left:3px solid #D1A35B;border-radius:6px;margin-top:15px;color:#294356;font-size:15px}.related{margin:40px 0}.related h2{font-size:23px}.related-links{display:flex;gap:10px;flex-wrap:wrap}.related-links a,.link-button{display:inline-flex;align-items:center;min-height:44px;border-radius:8px;padding:9px 18px;background:#176A91;color:#fff;font-size:14px}.related-links a{background:#EAF3F7;color:#176A91}.module{padding:46px 0;border-bottom:1px solid #DCE6EC}.module h2{font-size:23px;color:#173044;margin:0 0 18px}.module h3{font-size:18px;color:#173044}.module p{margin:6px 0 14px}.hero{padding:46px 0 24px}.hero-inner{display:grid;grid-template-columns:1fr;gap:20px}.hero-desc{max-width:800px}.hero-actions,.links-row{display:flex;gap:12px;flex-wrap:wrap;margin-top:20px}.link-button.secondary{background:white;border:1px solid #176A91;color:#176A91}.visual{display:flex;justify-content:center;align-items:center;min-width:0}.banner-visual{margin-top:25px}.banner-visual img{max-width:1120px;max-height:260px}.feature-grid{display:grid;grid-template-columns:1.5fr 1fr;gap:22px}.feature-card,.mini-card{min-width:0;background:#fff;border:1px solid #DCE6EC;border-radius:12px;padding:22px}.feature-card img{max-width:480px;max-height:220px;margin:0 auto 16px}.mini-card{padding:19px}.stack{display:grid;gap:16px}.explore{display:grid;grid-template-columns:1.4fr 1fr;gap:18px}.explore .tall{grid-row:span 2}.explore img{max-width:360px;max-height:160px;margin:auto}.flex-row{display:grid;grid-template-columns:1fr 1fr;gap:28px;align-items:center}.flex-row>*{min-width:0}.flex-row img{max-width:480px;max-height:220px;margin:auto}.light-blue{background:#EAF3F7}.sand{background:#F7F1E6}.index-cols{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.index-cols a{display:block;padding:9px 0}.image-small img{max-width:360px;max-height:160px}.app-art img{max-width:220px;max-height:320px}.icon-small img{max-width:48px;max-height:48px}.breadcrumbs a{color:#176A91}.directory{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.directory section{background:#fff;padding:20px;border:1px solid #DCE6EC;border-radius:12px}.directory a{display:block;padding:9px 0;border-bottom:1px solid #edf1f3}.directory small{display:block;color:#607789;font-size:13px}.faq-item h2{font-size:19px}.editor-note{font-size:14px;color:#607789}.inline-image{margin:20px auto;max-width:480px;max-height:220px}@media(max-width:1100px){.primary{gap:11px}.primary a{font-size:13px}.nav-shell{gap:13px}.desk-link:last-child{display:none}}@media(max-width:900px){.primary a:nth-child(n+4){display:none}.topic-inner{overflow-x:auto;white-space:nowrap}.topic-inner a{flex-shrink:0}}@media(max-width:767px){body{font-size:15px}.container{padding:0 16px}.nav-shell{height:60px;min-height:60px;padding:0 16px;justify-content:space-between;gap:8px}.brand{font-size:18px}.brand small,.brand-logo{display:none}.primary,.desk-link,.topic-strip{display:none}.header-right{gap:9px;margin-left:auto}.mobile-dir{display:inline-flex!important;font-size:14px}.mobile-menu-button{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:44px;border:1px solid #DCE6EC;border-radius:8px;background:#EAF3F7;padding:6px 10px;font-size:14px;color:#173044}.mobile-categories:not([hidden]){display:block;position:absolute;top:100%;left:0;right:0;background:#fff;border-bottom:1px solid #DCE6EC;box-shadow:0 12px 22px #1232471a;max-height:calc(100dvh - 60px);overflow-y:auto;padding:12px 16px 18px}.menu-group{padding:8px 0}.menu-group strong{color:#173044;font-size:14px}.menu-links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;margin-top:6px}.menu-links a{min-height:44px;display:flex;align-items:center;padding:8px 12px;border:1px solid #DCE6EC;border-radius:8px;font-size:14px}.page-hero h1,.hero h1{font-size:25px}.page-hero{padding:28px 0}.module{padding:32px 0}.module h2,.article-section h2,.related h2{font-size:21px}.module h3{font-size:17px}.article-section{padding:16px 18px}.feature-grid,.explore,.flex-row,.directory,.index-cols,.footer-lead{grid-template-columns:1fr}.explore .tall{grid-row:auto}.banner-visual img{max-height:170px}.flex-row img,.inline-image{max-width:100%;max-height:180px}.feature-card img,.explore img{max-width:100%;max-height:180px}.app-art img{max-width:190px;max-height:280px}.footer{margin-top:40px}.footer-inner{padding:28px 16px 85px}.footer-links{grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.bottom-nav{display:grid;grid-template-columns:repeat(5,1fr);position:fixed;bottom:0;left:0;right:0;background:#fff;border-top:1px solid #DCE6EC;height:calc(56px + env(safe-area-inset-bottom));padding-bottom:env(safe-area-inset-bottom);z-index:6;box-shadow:0 -4px 20px #17304412}.bottom-nav a{display:flex;flex-direction:column;align-items:center;justify-content:center;color:#294356;font-size:11px;line-height:1.2;min-width:0}.bottom-nav span{font-size:20px;line-height:1.3}}@media(max-width:340px){.menu-links{grid-template-columns:1fr}.brand{font-size:16px}.nav-shell{padding:0 12px}.header-right{gap:6px}}
/* Safe intrinsic sizing and symmetric mobile layout */
html,body{width:100%;max-width:100%;min-width:0}
main,.site-header,.footer,.page-hero,.module,.hero{max-width:100%;min-width:0}
.container,.nav-shell,.topic-inner,.footer-inner{width:100%;max-width:1120px;min-width:0;margin-inline:auto}
.container *,.feature-grid>*,.explore>*,.directory>*,.footer-links>*,.footer-lead>*,.index-cols>*,.stack>*,.hero-inner>*,.header-right,.primary{min-width:0}
img,svg,video,iframe{max-width:100%;height:auto}
p,h1,h2,h3,a,small,strong{overflow-wrap:break-word}
.banner-wrap,.banner-visual{width:100%;max-width:100%;min-width:0;display:flex;align-items:center;justify-content:center}
.banner-wrap img,.banner-visual img{display:block;max-width:100%;width:auto;height:auto;max-height:260px;object-fit:contain;margin-inline:auto}
.feature-card,.mini-card,.article-section,.directory section{max-width:100%;min-width:0}
@media(max-width:1024px){.nav-shell{gap:10px}.primary{gap:9px}.topic-inner{max-width:100%;overflow-x:auto}}
@media(max-width:767px){
 .container,.nav-shell,.topic-inner,.footer-inner{width:calc(100% - 32px);max-width:1120px;margin-inline:auto;padding-left:0;padding-right:0}
 .nav-shell{gap:6px}.brand,.header-right{min-width:0}.brand{font-size:18px;flex-shrink:1;white-space:nowrap}
 .mobile-dir{min-height:44px;align-items:center;padding:0 2px}.mobile-menu-button{flex-shrink:0}
 .hero-inner,.feature-grid,.explore,.flex-row,.directory,.index-cols,.footer-lead{grid-template-columns:minmax(0,1fr)}
 .feature-card,.mini-card,.article-section,.directory section{overflow-wrap:anywhere}
 .banner-wrap img,.banner-visual img{max-width:100%;width:auto;height:auto;max-height:170px}
 .footer-links{grid-template-columns:repeat(2,minmax(0,1fr))}
 .mobile-categories:not([hidden]){max-width:100%;box-sizing:border-box}
 .bottom-nav{width:100%;left:0;right:0;grid-template-columns:repeat(5,minmax(0,1fr))}
 .bottom-nav a{min-width:0;overflow-wrap:anywhere}
}
@media(min-width:768px) and (max-width:1024px){.banner-wrap img,.banner-visual img{max-height:220px}}
@media(max-width:340px){.nav-shell{width:calc(100% - 32px)}.brand{font-size:16px}.mobile-menu-button{padding-inline:7px}.footer-links{grid-template-columns:minmax(0,1fr)}}