:root{--bg:#F6FAFC;--surface:#fff;--pale:#EAF6FA;--pale2:#EDF4F8;--aqua:#25C8D1;--sky:#25B6E8;--blue:#1787DB;--navy:#174B78;--title:#183A56;--body:#31485D;--muted:#687D8E;--border:#DCE9F0;--footer:#123653;--container:1180px;--radius:16px}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:28px}body{margin:0;background:var(--bg);color:var(--body);font:16px/1.8 Arial,"PingFang SC","Microsoft YaHei",sans-serif;overflow-x:hidden}body.drawer-open{overflow:hidden}img{max-width:100%}a{color:var(--navy);text-underline-offset:4px}a:hover{color:var(--blue)}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--aqua);outline-offset:3px}button{font:inherit;cursor:pointer}h1,h2,h3,p{margin-top:0}h1,h2,h3{color:var(--title);line-height:1.38}h1{font-size:clamp(32px,3.1vw,42px);letter-spacing:-.025em}h2{font-size:clamp(23px,2.2vw,27px)}h3{font-size:19px}p{margin-bottom:1.1em}.container{width:min(var(--container),calc(100% - 56px));margin-inline:auto}.content-section{margin-block:56px}.section-head{max-width:750px;margin-bottom:24px}.section-kicker,.eyebrow{display:block;font-size:13px;font-weight:800;letter-spacing:.12em;color:var(--blue);margin-bottom:10px}.section-intro{max-width:760px;color:var(--muted)}.skip-link{position:absolute;top:-90px;left:12px;z-index:1100;padding:8px 14px;background:#fff}.skip-link:focus{top:8px}.site-header{background:var(--surface);border-bottom:1px solid var(--border);position:relative;z-index:30}.topbar{height:72px;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{text-decoration:none;display:flex;align-items:center;min-width:145px}.brand-text{font-size:21px;font-weight:800;color:var(--navy);line-height:1.25}.brand-text small{display:block;font-size:10px;letter-spacing:.14em}.topline{color:var(--muted);font-size:14px;margin:0}.entry-button,.button-primary{background:var(--navy);color:#fff;text-decoration:none;padding:9px 21px;border-radius:9px;font-weight:700;white-space:nowrap;display:inline-flex;align-items:center;gap:12px}.entry-button:hover,.button-primary:hover{background:#21639b;color:white}.desktop-nav{background:var(--navy)}.nav-row{display:flex;align-items:center;justify-content:space-between;gap:18px;min-height:48px}.nav-row a{display:inline-flex;align-items:center;height:48px;color:#e8f5fa;text-decoration:none;font-size:14px;white-space:nowrap;border-bottom:3px solid transparent;padding-top:3px}.nav-row a:hover,.nav-row a[aria-current=page]{color:white;border-bottom-color:var(--aqua)}.menu-toggle{display:none;width:40px;height:40px;border:1px solid var(--border);background:white;border-radius:9px;padding:10px;flex-direction:column;justify-content:space-around}.menu-toggle span{display:block;height:2px;background:var(--navy);border-radius:1px}.drawer-overlay{position:fixed;inset:0;background:rgba(6,29,50,.47);visibility:hidden;opacity:0;pointer-events:none;transition:opacity .2s;z-index:90}.drawer-overlay.is-open{visibility:visible;opacity:1;pointer-events:auto}.mobile-drawer{position:fixed;z-index:91;top:0;bottom:0;left:0;width:min(86vw,344px);background:#fff;overflow-y:auto;padding:21px 23px;visibility:hidden;transform:translateX(-100%);transition:transform .22s,visibility .22s;box-shadow:10px 0 30px rgba(0,0,0,.08)}.mobile-drawer.is-open{transform:translateX(0);visibility:visible}.drawer-head{display:flex;align-items:center;justify-content:space-between;font-size:20px;font-weight:800;color:var(--title);border-bottom:1px solid var(--border);padding-bottom:14px}.drawer-close{background:transparent;border:0;font-size:30px;color:var(--title)}.drawer-group{margin-top:23px}.drawer-group p{font-size:13px;color:var(--muted);font-weight:800;margin-bottom:7px}.drawer-group a{display:block;padding:8px 4px;text-decoration:none;border-bottom:1px solid #edf3f6}.mobile-bottom{display:none}.site-footer{background:var(--footer);color:#d7e9f4;margin-top:68px;padding:40px 0 18px}.footer-grid{display:grid;grid-template-columns:1.1fr 1fr;gap:80px}.footer-brand{font-size:25px;font-weight:800;color:white;line-height:1.3}.footer-brand small{display:block;font-size:12px;letter-spacing:.13em}.site-footer h2{font-size:17px;color:white}.footer-links{display:flex;flex-wrap:wrap;gap:8px 20px}.site-footer a{color:#eaf7ff}.footer-bottom{border-top:1px solid #37607a;display:flex;justify-content:space-between;gap:20px;margin-top:24px;padding-top:19px;font-size:12px;color:#d7e9f4}.to-top{position:fixed;right:22px;bottom:25px;background:var(--navy);color:white;border:0;border-radius:50%;width:42px;height:42px;opacity:0;visibility:hidden;z-index:20;transition:opacity .2s}.to-top.is-visible{opacity:1;visibility:visible}
.media{display:flex;align-items:center;justify-content:center;width:100%;min-width:0;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--logo{width:auto;height:38px;max-width:220px;background:transparent;border-radius:0}.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:360px;margin:auto}.media--wide{width:100%}.media--placeholder{background:linear-gradient(135deg,#eaf6fa,#edf4f8);border:1px solid var(--border)}
.hero{background:linear-gradient(120deg,#fff 25%,#eaf6fa);border-bottom:1px solid var(--border)}.hero-grid{display:grid;grid-template-columns:56fr 44fr;gap:42px;align-items:center;padding-block:43px}.hero-copy h1{margin-bottom:20px}.hero-copy p{max-width:610px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:22px}.button-outline{display:inline-flex;padding:8px 19px;border:1px solid #8fb6d1;text-decoration:none;border-radius:9px;font-weight:700}.quick-strip{background:white;border-bottom:1px solid var(--border)}.quick-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:28px;padding:17px 0}.quick-group{min-width:0;display:flex;flex-wrap:wrap;align-items:baseline;gap:8px 11px;font-size:13px}.quick-group strong{color:var(--title)}.quick-group a{text-decoration:none}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.topic-card{display:block;background:#fff;border:1px solid var(--border);border-radius:13px;padding:21px;text-decoration:none;min-height:164px;transition:border-color .2s,transform .2s}.topic-card:hover{border-color:var(--sky);transform:translateY(-2px)}.topic-card h3{font-size:18px;margin:0 0 9px}.topic-card p{font-size:14px;color:var(--muted);line-height:1.65;margin:0}.feature-editor{display:grid;grid-template-columns:2fr 1fr;gap:22px}.feature-lead{background:var(--pale);border-radius:17px;padding:30px;min-height:270px}.feature-stack{display:grid;gap:16px}.feature-small{background:white;padding:20px 24px;border-radius:13px;border:1px solid var(--border)}.feature-small h3{margin-bottom:6px}.feature-small p{font-size:14px;margin-bottom:6px}.story-split{display:grid;grid-template-columns:1fr 1fr;align-items:center;gap:42px}.story-split.reverse> :first-child{order:2}.story-split.reverse> :last-child{order:1}.story-split p{max-width:600px}.text-link{font-weight:700}.mini-rule-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.mini-rule{background:white;border-top:4px solid var(--aqua);padding:22px 24px;border-radius:12px;box-shadow:0 3px 15px rgba(21,66,93,.04)}.mini-rule h3{margin-bottom:10px}.step-track{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;counter-reset:step}.step-track>div{background:var(--pale2);border-radius:12px;padding:20px;position:relative}.step-track>div:before{counter-increment:step;content:'0' counter(step);font-size:13px;font-weight:bold;color:var(--blue)}.step-track h3{margin:7px 0}.editor-note{border-top:1px solid var(--border);padding:23px 0;color:var(--muted);font-size:14px}
.page-intro{padding-top:40px;padding-bottom:14px;max-width:940px}.page-intro h1{font-size:clamp(29px,2.9vw,36px)}.page-intro .lead{font-size:17px;line-height:1.85;max-width:800px}.article-main{max-width:780px}.article-main h2{margin-top:30px}.article-main p{line-height:1.85}.content-panel{background:white;border:1px solid var(--border);border-radius:15px;padding:27px}.content-panel--tint{background:var(--pale)}.section-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px;align-items:start}.section-grid--thirds{grid-template-columns:repeat(3,1fr)}.section-grid>*{min-width:0}.comparison-scroll{overflow-x:auto;max-width:100%;border:1px solid var(--border);border-radius:13px;background:white}.comparison{border-collapse:collapse;min-width:620px;width:100%;line-height:1.65;font-size:15px}.comparison th,.comparison td{padding:15px 17px;text-align:left;border-bottom:1px solid var(--border);vertical-align:top}.comparison th{background:var(--pale);color:var(--title)}.comparison tr:last-child td{border-bottom:none}.linear-steps{list-style:none;padding:0;counter-reset:step}.linear-steps li{position:relative;border-left:3px solid var(--aqua);padding:0 0 20px 26px;margin-left:11px}.linear-steps li:before{counter-increment:step;content:counter(step);position:absolute;left:-14px;top:0;border-radius:50%;width:25px;height:25px;display:grid;place-items:center;background:var(--navy);color:white;font-size:12px}.linear-steps li strong{display:block;color:var(--title)}.linear-steps li p{margin:6px 0 0}.article-aside-layout{display:grid;grid-template-columns:minmax(0,760px) minmax(0,240px);gap:40px;align-items:start}.glossary{background:var(--pale2);border:1px solid var(--border);border-radius:13px;padding:18px}.glossary dt{font-weight:800;color:var(--title)}.glossary dd{margin:3px 0 15px;font-size:14px}.anchor-index{display:flex;flex-wrap:wrap;gap:9px;margin:19px 0}.anchor-index a{padding:6px 12px;border:1px solid var(--border);background:white;text-decoration:none;border-radius:7px;font-size:14px}.related-links{margin-block:55px;border-top:1px solid var(--border);padding-top:27px}.related-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.related-link{border:1px solid var(--border);border-radius:12px;background:white;text-decoration:none;padding:19px;display:flex;flex-direction:column;gap:8px}.related-link span:nth-child(2){font-size:13px;color:var(--muted);flex:1}.related-link span:last-child{color:var(--blue)}.gallery-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px}.gallery-item{background:white;border:1px solid var(--border);padding:14px;border-radius:15px}.gallery-item figcaption{padding:12px 7px 4px;font-size:14px}.gallery-item h3{margin:0 0 6px}.gallery-item p{margin:0}.notice{border-left:4px solid var(--blue);background:var(--pale2);padding:18px 22px;border-radius:0 10px 10px 0}.faq{margin:14px 0;border:1px solid var(--border);border-radius:11px;background:white}.faq summary{padding:13px 18px;cursor:pointer;font-weight:700;color:var(--title)}.faq p{padding:0 18px 15px;margin:0}.service-table{font-size:14px}.tag{display:inline-block;padding:3px 11px;background:#e5f6f9;color:#126184;border-radius:5px;font-size:12px;font-weight:700}.reading-steps{margin-top:25px}
@media(max-width:1100px){.topic-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.container{width:calc(100% - 44px)}}
@media(max-width:980px){.desktop-nav{display:none}.menu-toggle{display:flex}.topbar{height:64px;position:relative;justify-content:space-between}.brand{position:absolute;left:50%;transform:translateX(-50%);min-width:0;max-width:45%}.media--logo{height:30px;max-width:175px}.topline{display:none}.entry-button{margin-left:auto;padding:7px 10px;font-size:13px;height:40px}.brand-text{font-size:17px}.brand-text small{font-size:8px}.topbar{gap:8px}.hero-grid{gap:24px}}
@media(max-width:760px){.hero-grid,.story-split,.section-grid,.feature-editor,.article-aside-layout,.footer-grid{grid-template-columns:1fr}.hero-grid{padding-block:30px}.hero-grid> :last-child{order:2}.story-split.reverse> :first-child{order:0}.story-split.reverse> :last-child{order:0}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.feature-stack{grid-template-columns:1fr 1fr}.mini-rule-grid,.section-grid--thirds,.related-grid{grid-template-columns:1fr 1fr}.quick-grid{grid-template-columns:1fr;gap:7px}.gallery-grid{grid-template-columns:1fr 1fr}.step-track{grid-template-columns:1fr 1fr}.footer-grid{gap:20px}.footer-bottom{display:block}.article-aside-layout .glossary{max-width:none}}
@media(max-width:640px){.container{width:calc(100% - 32px)}body{font-size:15px;line-height:1.78}h1{font-size:clamp(27px,7vw,31px)}h2{font-size:clamp(20px,5vw,23px)}h3{font-size:17px}.content-section{margin-block:34px}.section-head{margin-bottom:19px}.hero-grid{gap:24px}.hero-actions a{font-size:14px}.topic-grid,.gallery-grid,.mini-rule-grid,.related-grid,.feature-stack{grid-template-columns:1fr}.topic-card{min-height:0;padding:17px}.section-grid{grid-template-columns:1fr}.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--banner{height:150px}.media--mobile{height:290px;max-width:250px}.media--logo{height:29px;max-width:145px}.content-panel,.feature-lead,.mini-rule{padding:19px}.feature-editor{gap:14px}.page-intro{padding-top:28px}.page-intro h1{font-size:clamp(25px,6vw,29px)}.page-intro .lead{font-size:15px}.mobile-bottom{display:grid;grid-template-columns:repeat(4,1fr);position:fixed;z-index:25;bottom:0;left:0;right:0;background:white;border-top:1px solid var(--border);padding-bottom:env(safe-area-inset-bottom)}.mobile-bottom a{text-align:center;padding:10px 0;color:var(--body);text-decoration:none;font-size:13px;font-weight:700}.mobile-bottom a[aria-current=page]{color:var(--blue);box-shadow:inset 0 3px var(--aqua)}body{padding-bottom:calc(47px + env(safe-area-inset-bottom))}.to-top{bottom:calc(62px + env(safe-area-inset-bottom));right:13px}.site-footer{margin-top:40px}.step-track{grid-template-columns:1fr 1fr}.footer-brand{font-size:21px}.entry-button{font-size:12px;padding:6px 9px;gap:3px}}
@media(max-width:360px){.entry-button{padding:5px 7px}.brand-text{font-size:15px}.brand{max-width:42%}.step-track{grid-template-columns:1fr}}
@media(max-height:450px) and (max-width:640px){.mobile-bottom{position:static}body{padding-bottom:0}.to-top{bottom:18px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;animation-duration:.01ms!important;transition-duration:.01ms!important}}