:root{--bg:#f5fbff;--white:#fff;--pale:#eaf7fc;--pale2:#dff5fb;--cyan:#25c8d1;--sky:#25b6e8;--blue:#1787db;--deep:#174b78;--title:#173b60;--text:#2d4359;--muted:#687f93;--border:#dcebf3;--shadow:0 12px 38px rgba(23,75,120,.07)}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:95px}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}body.menu-open{overflow:hidden}a{color:var(--deep);text-decoration:none}a:hover{color:#117db0}button{font:inherit}img{max-width:100%}.wrap{width:min(1160px,calc(100% - 48px));margin:0 auto}.skip-link{position:absolute;top:-80px;left:14px;background:#fff;padding:12px;z-index:200}.skip-link:focus{top:10px}.site-header{position:sticky;top:0;background:rgba(255,255,255,.97);border-bottom:1px solid var(--border);z-index:50;backdrop-filter:blur(12px)}.header-inner{min-height:72px;display:flex;gap:22px;align-items:center}.brand{display:flex;align-items:center;gap:10px;color:var(--title);min-width:max-content}.brand img{display:block;width:auto;max-width:180px;height:38px;object-fit:contain}.brand-mark{background:linear-gradient(125deg,var(--cyan),var(--blue));color:white;width:42px;height:42px;border-radius:12px;display:grid;place-items:center;font-size:25px;font-weight:800}.brand-type{font-size:19px;font-weight:800;line-height:1.2}.brand-type small{display:block;letter-spacing:1.5px;color:var(--muted);font-size:9px;font-weight:700;margin-top:5px}.desktop-nav{display:flex;align-items:center;justify-content:center;gap:clamp(10px,1.35vw,24px);margin-left:auto}.desktop-nav a{white-space:nowrap;color:var(--deep);font-size:14px;font-weight:700;padding:23px 0;border-bottom:3px solid transparent;line-height:1.4}.desktop-nav a:hover,.desktop-nav a.is-active{color:#119eb6;border-bottom-color:var(--cyan)}.main-btn{display:inline-flex;align-items:center;justify-content:center;min-width:82px;min-height:42px;padding:0 20px;border-radius:999px;background:linear-gradient(110deg,#25c8d1,#25b6e8,#1787db);color:#fff;font-weight:700;white-space:nowrap;box-shadow:0 8px 16px rgba(23,135,219,.15)}.main-btn:hover{color:#fff;filter:brightness(.95)}.header-entry{font-size:14px}.menu-toggle{display:none;border:0;background:none;width:40px;height:40px;padding:9px;cursor:pointer;flex:none}.menu-toggle span{display:block;width:22px;height:2px;border-radius:2px;background:var(--deep);margin:5px 0}.drawer-overlay{position:fixed;inset:0;background:rgba(11,37,61,.46);z-index:90;visibility:hidden;opacity:0;pointer-events:none;transition:opacity .2s,visibility .2s}.drawer-overlay.is-visible{visibility:visible;opacity:1;pointer-events:auto}.drawer{position:fixed;top:0;bottom:0;left:0;width:min(86vw,340px);overflow:auto;background:white;z-index:100;transform:translateX(-103%);visibility:hidden;transition:transform .23s,visibility .23s;box-shadow:var(--shadow)}.drawer.is-open{transform:translateX(0);visibility:visible}.drawer-header{display:flex;justify-content:space-between;align-items:center;padding:18px 20px;border-bottom:1px solid var(--border)}.drawer-title{font-size:20px;font-weight:800;color:var(--title);line-height:1.25}.drawer-title small{display:block;font-size:10px;color:var(--muted);letter-spacing:1px}.drawer-close{border:0;background:var(--pale);border-radius:50%;width:36px;height:36px;font-size:26px;color:var(--deep);cursor:pointer}.drawer-nav{padding:8px 20px 28px}.drawer-group{margin:18px 0}.drawer-group strong{display:block;font-size:12px;letter-spacing:2px;color:#6b8798;border-bottom:1px solid var(--border);padding:0 4px 8px}.drawer-group a{display:block;padding:8px 6px;border-bottom:1px solid #edf5fa;font-size:15px}.drawer-group a.is-active{color:#138fbd;font-weight:700}.page{padding:42px 0 75px}.eyebrow{font-size:12px;font-weight:800;letter-spacing:2.5px;color:#158faa;text-transform:uppercase}.lead{max-width:760px;font-size:17px;line-height:1.9;color:#46627a}.hero{display:grid;grid-template-columns:1.06fr .94fr;align-items:center;gap:36px;padding:54px 0 40px}.hero h1{font-size:40px;line-height:1.35;margin:12px 0 19px;color:var(--title);letter-spacing:-.8px}.hero p{max-width:570px;font-size:17px;line-height:1.92}.hero-cta{display:flex;gap:12px;flex-wrap:wrap;margin-top:26px}.plain-btn{display:inline-flex;justify-content:center;align-items:center;min-height:43px;border:1px solid #c8e4f2;border-radius:999px;padding:0 18px;color:var(--deep);font-weight:700;background:#fff}.media{display:flex;align-items:center;justify-content:center;width:100%;overflow:hidden;background:var(--pale);border-radius:16px;min-height:160px}.media img{display:block;width:auto;height:auto;max-width:100%;max-height:100%;object-fit:contain;object-position:center}.media-missing{flex-direction:column;gap:5px;background:linear-gradient(140deg,#ecfbff,#dff5fb 55%,#d7edfa);border:1px solid #d5e9f3}.media-symbol{font-size:62px;color:#8ccddb;line-height:1}.media-placeholder-label{font-size:13px;color:#57839d;letter-spacing:.6px}.hero-media{height:310px}.hero-media img{max-height:310px}.wide-media{height:245px}.wide-media img{max-height:245px}.card-media{height:168px}.card-media img{max-height:168px}.portrait-media{height:340px}.portrait-media img{max-height:340px}.section{margin-top:42px}.section-heading{display:flex;justify-content:space-between;gap:16px;align-items:end;margin-bottom:20px}.section h2,.section-heading h2{font-size:26px;line-height:1.4;margin:0 0 8px;color:var(--title)}.section-heading p{margin:0;color:var(--muted);font-size:14px}.text-link{font-size:14px;color:#117baf;white-space:nowrap;font-weight:700}.panel{background:#fff;border:1px solid var(--border);box-shadow:var(--shadow);border-radius:18px;padding:26px}.feature-split{display:grid;grid-template-columns:1.05fr .95fr;align-items:center;gap:28px}.feature-split.reverse{grid-template-columns:.95fr 1.05fr}.feature-split h2{font-size:27px;color:var(--title);margin:9px 0 12px}.feature-split h3{color:var(--title)}.feature-split p{line-height:1.85}.tiles{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.tile{display:block;background:#fff;border:1px solid var(--border);border-radius:16px;padding:22px;transition:transform .18s,box-shadow .18s}.tile:hover{transform:translateY(-2px);box-shadow:var(--shadow)}.tile-label{font-size:12px;color:#138eae;font-weight:800;letter-spacing:1.4px}.tile h3{font-size:19px;line-height:1.45;margin:8px 0;color:var(--title)}.tile p{font-size:14px;color:#5d7688;line-height:1.75;margin:0}.tile .arrow{display:block;margin-top:14px;color:#0b89b4;font-size:14px;font-weight:700}.reading-grid{display:grid;grid-template-columns:1.25fr .75fr;gap:20px}.read-list{list-style:none;margin:0;padding:0}.read-list li{padding:14px 0;border-bottom:1px solid var(--border)}.read-list li:last-child{border:0}.read-list a{font-weight:700}.read-list small{display:block;color:var(--muted);font-size:13px}.page-intro{padding:46px 0 26px;border-bottom:1px solid var(--border)}.page-intro h1{font-size:34px;color:var(--title);line-height:1.4;margin:8px 0 14px}.page-intro .lead{margin:0}.article{max-width:820px;margin:0 auto}.article h2{font-size:25px;line-height:1.5;color:var(--title);margin:35px 0 12px}.article h3{font-size:19px;color:var(--title);margin:24px 0 9px}.article p{margin:12px 0;line-height:1.86}.article ul,.article ol{padding-left:24px}.article li{margin:8px 0}.article .wide-media{margin:25px 0}.note{border-left:4px solid var(--cyan);background:var(--pale);padding:17px 20px;border-radius:0 12px 12px 0;margin:24px 0}.comparison{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.comparison .panel h3{color:var(--title);margin-top:0}.comparison p{font-size:15px}.stat-strip{display:grid;grid-template-columns:repeat(3,1fr);gap:15px;margin:22px 0}.stat-strip div{background:var(--pale);padding:22px;border-radius:14px}.stat-strip strong{display:block;font-size:17px;color:var(--title)}.stat-strip span{font-size:13px;color:var(--muted)}.toc{display:flex;gap:8px;flex-wrap:wrap;margin:22px 0}.toc a{background:white;border:1px solid var(--border);border-radius:30px;padding:7px 13px;font-size:14px}.story-layout{display:grid;grid-template-columns:minmax(0,1fr) 250px;gap:36px;align-items:start}.aside-index{position:sticky;top:98px;padding:20px;border-radius:15px;background:white;border:1px solid var(--border)}.aside-index strong{color:var(--title)}.aside-index a{display:block;border-top:1px solid var(--border);padding:10px 0;font-size:14px}.numbered{counter-reset:chapter}.chapter{position:relative;padding-left:48px;margin:24px 0}.chapter:before{counter-increment:chapter;content:counter(chapter,decimal-leading-zero);position:absolute;left:0;top:0;font-weight:800;color:#16aac4;font-size:21px}.chapter h3{margin:0 0 7px}.definition-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:15px}.definition-grid .panel{padding:20px}.definition-grid dt{font-weight:800;color:var(--title)}.definition-grid dd{margin:7px 0 0;font-size:14px}.table-scroller{overflow-x:auto;border:1px solid var(--border);border-radius:14px;background:#fff}.knowledge-table{width:100%;border-collapse:collapse;min-width:550px}.knowledge-table th,.knowledge-table td{text-align:left;padding:14px 17px;border-bottom:1px solid var(--border);vertical-align:top;font-size:14px}.knowledge-table th{color:var(--title);background:var(--pale);font-size:14px}.knowledge-table tr:last-child td{border-bottom:0}.visual-gallery{display:grid;grid-template-columns:1.1fr .9fr;gap:18px}.visual-gallery .panel{padding:18px}.visual-gallery .panel h3{color:var(--title);margin:12px 0 4px}.visual-gallery .panel p{font-size:14px;margin:0}.faq details{border-bottom:1px solid var(--border);padding:14px 0}.faq summary{cursor:pointer;font-size:16px;font-weight:700;color:var(--title)}.faq details p{font-size:15px;margin:8px 0}.related{margin-top:52px;padding:25px;background:var(--pale);border-radius:16px}.related h2{font-size:20px;color:var(--title);margin:0 0 10px}.related a{display:inline-flex;margin:5px 16px 5px 0;font-weight:700;font-size:14px}.site-footer{background:#123653;color:#eaf7ff;padding:44px 0 18px}.footer-grid{display:grid;grid-template-columns:1.35fr 1fr 1fr;gap:40px}.footer-name{font-size:22px;font-weight:800}.footer-name span{display:block;font-size:11px;letter-spacing:2px;color:#9edce8}.site-footer h2{font-size:17px;margin:0 0 13px;color:white}.site-footer p{font-size:14px;color:#d1e5ee;line-height:1.8}.site-footer .footer-note{font-size:12px;color:#a8c9d7}.footer-links{display:grid;grid-template-columns:1fr 1fr;gap:7px 12px}.site-footer a{color:#e0f7fc;font-size:14px}.site-footer a:hover{color:#7fe4ef}.footer-bottom{display:flex;justify-content:space-between;gap:10px;border-top:1px solid rgba(255,255,255,.15);margin-top:30px;padding-top:16px;font-size:12px;color:#b5d3de}.footer-bottom a{font-size:12px}.mobile-bottom{display:none}.back-top{position:fixed;right:24px;bottom:25px;z-index:45;width:43px;height:43px;border-radius:50%;border:0;background:var(--deep);color:#fff;box-shadow:var(--shadow);cursor:pointer;opacity:0;visibility:hidden;transition:opacity .18s}.back-top.visible{opacity:1;visibility:visible}.muted{color:var(--muted)}.accent-quote{font-size:21px;color:var(--title);font-weight:700;line-height:1.65;margin:24px 0;padding-left:18px;border-left:4px solid var(--cyan)}
@media(max-width:1120px){.desktop-nav{gap:11px}.desktop-nav a{font-size:13px}.header-inner{gap:12px}.brand-type{font-size:17px}}
@media(max-width:980px){.desktop-nav{display:none}.menu-toggle{display:block}.header-inner{justify-content:space-between;min-height:60px;position:relative}.brand{position:absolute;left:50%;transform:translateX(-50%)}.brand img{max-width:143px;height:29px}.brand-mark{width:32px;height:32px;font-size:19px;border-radius:9px}.brand-type{font-size:16px}.brand-type small{font-size:8px}.header-entry{min-height:40px;padding:0 13px;font-size:12px}.hero{gap:22px}.hero h1{font-size:34px}.footer-grid{gap:20px}}
@media(max-width:700px){.wrap{width:calc(100% - 32px)}.page{padding:20px 0 64px}.hero{display:flex;flex-direction:column-reverse;align-items:stretch;gap:20px;padding:22px 0 16px}.hero h1{font-size:29px}.hero p{font-size:15px;margin:12px 0}.hero-media{height:210px}.hero-media img{max-height:210px}.section{margin-top:28px}.section h2,.section-heading h2{font-size:22px}.section-heading{align-items:start}.tiles{grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.tile{padding:17px}.tile h3{font-size:17px}.tile p{font-size:13px}.reading-grid,.feature-split,.feature-split.reverse,.comparison,.story-layout,.visual-gallery{grid-template-columns:1fr}.feature-split{gap:17px}.feature-split h2{font-size:22px}.panel{padding:20px}.page-intro{padding:20px 0 23px}.page-intro h1{font-size:27px}.lead{font-size:15px}.article h2{font-size:21px}.article h3{font-size:18px}.article p{font-size:15px}.aside-index{position:static}.definition-grid{grid-template-columns:1fr}.stat-strip{grid-template-columns:1fr}.stat-strip div{padding:15px}.wide-media{height:185px}.wide-media img{max-height:185px}.card-media{height:140px}.card-media img{max-height:140px}.portrait-media{height:270px}.portrait-media img{max-height:270px}.footer-grid{grid-template-columns:1fr;gap:20px}.footer-bottom{display:block}.footer-bottom a{display:block;margin-top:7px}.site-footer{padding-bottom:75px}.mobile-bottom{position:fixed;z-index:60;bottom:0;left:0;right:0;display:grid;grid-template-columns:repeat(4,1fr);background:white;border-top:1px solid var(--border);padding-bottom:env(safe-area-inset-bottom)}.mobile-bottom a{text-align:center;display:block;padding:10px 2px;color:var(--deep);font-weight:700;font-size:13px}.mobile-bottom a[aria-current]{color:#079cbd;background:#effaff}.back-top{bottom:75px;right:14px}.footer-links{grid-template-columns:repeat(2,1fr)}}
@media(max-width:365px){.brand-type{font-size:14px}.brand-mark{width:28px;height:28px}.header-entry{padding:0 10px;font-size:11px}.tiles{grid-template-columns:1fr}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{transition-duration:.01ms!important}}