:root{--bg:#F6FAFC;--white:#fff;--soft:#EAF6FA;--soft2:#EDF4F8;--teal:#25C8D1;--sky:#25B6E8;--blue:#1787DB;--navy:#174B78;--ink:#183A56;--text:#31485D;--muted:#687D8E;--line:#DCE9F0;--footer:#123653;--shadow:0 8px 28px rgba(18,54,83,.055)}
*,*::before,*::after{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:26px}body{margin:0;background:var(--bg);font:16px/1.8 Arial,"PingFang SC","Microsoft YaHei",sans-serif;color:var(--text);overflow-x:hidden}img{max-width:100%}a{color:var(--navy);text-decoration:none}a:hover{color:var(--blue)}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--sky);outline-offset:3px}button{font:inherit;cursor:pointer}h1,h2,h3,h4,p{margin-top:0}h1,h2,h3{color:var(--ink);line-height:1.4}h1{font-size:clamp(27px,3.2vw,42px);letter-spacing:-.025em}h2{font-size:clamp(21px,2.2vw,27px)}h3{font-size:clamp(17px,1.7vw,21px)}p{margin-bottom:1.1em}ul,ol{padding-left:1.4em}li+li{margin-top:.45em}section[id],article[id]{scroll-margin-top:30px}.container{width:min(100% - 56px,1180px);margin-inline:auto}.skip-link{position:absolute;z-index:500;top:-80px;left:15px;padding:7px 16px;background:white}.skip-link:focus{top:10px}.site-header{background:#fff;position:relative;z-index:20;border-bottom:1px solid var(--line)}.topbar{min-height:72px;display:flex;align-items:center;gap:26px}.brand{display:flex;align-items:center;flex:0 1 auto;min-width:0}.brand .media--logo{height:38px;width:auto;min-width:0;max-width:190px;background:transparent;border-radius:0}.brand .media--logo img{height:100%;width:auto}.brand-fallback{font-weight:900;color:var(--navy);font-size:24px;letter-spacing:.06em;line-height:1.05}.brand-fallback span{color:#13aebc}.brand-fallback small{display:block;font-size:9px;letter-spacing:.3em;font-weight:700;margin-top:5px}.brand:has(.media:not(.media--empty)) .brand-fallback{display:none}.brand-caption{margin:0 auto;color:var(--muted);font-size:13px;letter-spacing:.2em}.entry-button,.button-primary{display:inline-flex;align-items:center;justify-content:center;gap:8px;flex:none;min-height:44px;background:var(--navy);color:#fff;border-radius:8px;padding:9px 22px;font-size:14px;font-weight:700;transition:background .2s,transform .2s}.entry-button:hover,.button-primary:hover{background:#116aab;color:#fff;transform:translateY(-1px)}.desktop-nav{background:var(--navy)}.nav-row{display:flex;align-items:stretch;justify-content:space-between;gap:4px;min-width:0}.nav-row a{color:#eaf7ff;white-space:nowrap;font-size:14px;padding:12px 13px;min-height:48px;border-bottom:3px solid transparent;font-weight:600}.nav-row a:hover,.nav-row a[aria-current]{color:white;background:rgba(255,255,255,.08);border-bottom-color:var(--teal)}.menu-toggle{display:none;border:0;background:transparent;width:40px;height:40px;align-items:center;justify-content:center;flex-direction:column;gap:5px;flex-shrink:0}.menu-toggle span{display:block;width:21px;height:2px;background:var(--ink);border-radius:2px}.quick-links{background:#eaf6fa;border-bottom:1px solid var(--line)}.quick-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px;padding-block:12px}.quick-grid>div{display:flex;align-items:center;gap:12px;flex-wrap:wrap;font-size:13px}.quick-grid strong{color:var(--navy);margin-right:3px}.quick-grid a{color:#526f82}.quick-grid a:hover{text-decoration:underline}.mobile-drawer,.drawer-overlay,.mobile-bottom{display:none}.section{padding-block:54px}.section--tint{background:var(--soft2)}.section--white{background:var(--white)}.section-heading{margin-bottom:24px;max-width:720px}.section-heading h2{margin:7px 0 8px}.section-heading p{color:var(--muted);margin:0}.eyebrow{display:inline-block;color:#087e9a;font-size:11px;font-weight:800;letter-spacing:.18em;text-transform:uppercase}.kicker{display:inline-block;color:#087e9a;font-weight:700;letter-spacing:.13em;font-size:12px;margin-bottom:12px}.hero{padding-block:54px 58px;background:linear-gradient(115deg,#fff 0%,#fff 47%,#ebf8fb 100%)}.hero-grid{display:grid;grid-template-columns:minmax(0,56fr) minmax(0,44fr);align-items:center;gap:46px}.hero h1{max-width:600px;margin:0 0 22px}.hero p{max-width:640px;font-size:16.5px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:26px}.button-secondary{border:1px solid #b9d8e7;border-radius:8px;color:var(--navy);background:#fff;padding:9px 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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--inline{height:220px}.media--logo{height:38px;width:auto}.media--empty{background:linear-gradient(145deg,#e7f4f8,#f1f8fa)}.media--empty::after{content:"";width:36%;height:1px;background:#c6e3eb;transform:rotate(-32deg)}.media--wide{height:auto;min-height:110px;max-height:240px;aspect-ratio:2.5/1}.media--portrait{max-width:330px;margin-inline:auto}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.topic-card{display:block;padding:21px;border:1px solid var(--line);background:white;border-radius:12px;transition:border-color .2s,transform 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minmax(0,1.04fr);gap:48px;align-items:center}.feature-grid--reverse{grid-template-columns:minmax(0,1.04fr) minmax(0,1fr)}.feature-copy h2{margin:8px 0 18px}.feature-copy p{max-width:570px}.feature-copy .text-link{display:inline-block;margin-top:8px}.rule-cards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.rule-card{padding:25px;background:white;border:1px solid var(--line);border-top:3px solid var(--teal);border-radius:10px}.rule-card h3{margin:8px 0 13px}.rule-card p{font-size:14.5px;min-height:90px}.reading-steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px}.step{padding:20px 20px 16px;border-top:2px solid var(--sky);background:var(--white)}.step span{color:#087f9a;font-weight:800;font-size:12px}.step h3{font-size:17px;margin:6px 0}.step p{font-size:13.5px;color:var(--muted);margin-bottom:0}.editor-note{padding-block:23px;border-top:1px solid var(--line);font-size:13.5px;color:var(--muted)}.page-intro{padding-block:45px 34px;background:#fff;border-bottom:1px solid var(--line)}.page-intro .container{max-width:1180px}.page-intro h1{font-size:clamp(25px,3vw,36px);margin:0 0 17px;max-width:960px}.page-intro p{max-width:780px;margin-bottom:0}.crumbs{color:var(--muted);font-size:12px;margin-bottom:15px}.crumbs a{text-decoration:underline}.article-section{padding-block:42px}.article-section+.article-section{border-top:1px solid var(--line)}.article-section h2{margin-bottom:18px}.article-section h3{margin:24px 0 9px}.article-section p{max-width:780px}.prose{max-width:780px}.prose p,.prose li{line-height:1.85}.content-rail{display:grid;grid-template-columns:minmax(0,780px) minmax(180px,240px);gap:50px;align-items:start}.rail-card{padding:22px;background:#eaf6fa;border:1px solid var(--line);border-radius:12px;position:sticky;top:18px}.rail-card h2{font-size:18px}.rail-card a{display:block;padding:9px 0;border-top:1px solid #d1e5ef;font-size:14px}.data-table-wrap{overflow-x:auto;margin:23px 0;border:1px solid var(--line);border-radius:10px;background:#fff}.data-table{width:100%;border-collapse:collapse;min-width:520px;font-size:14px}.data-table th{text-align:left;background:#eaf6fa;color:var(--ink);font-weight:800}.data-table th,.data-table td{padding:14px 16px;border-bottom:1px solid var(--line);vertical-align:top}.data-table tr:last-child td{border-bottom:0}.data-table th:first-child{min-width:112px}.info-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.info-card{padding:22px;background:white;border:1px solid var(--line);border-radius:11px}.info-card h3{margin:7px 0 12px}.info-card p{font-size:14px;margin:0}.timeline{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;counter-reset:stages}.timeline>div{padding:22px;background:#fff;border:1px solid var(--line);border-radius:10px}.timeline>div::before{counter-increment:stages;content:'0' counter(stages);font-weight:800;font-size:12px;color:#058ca1}.timeline h3{margin:12px 0}.timeline p{font-size:14px;margin:0}.callout{padding:21px 24px;background:#eaf6fa;border-left:4px solid var(--teal);border-radius:0 10px 10px 0;margin:24px 0;max-width:780px}.callout p:last-child{margin-bottom:0}.split-feature{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);align-items:center;gap:35px;margin:26px 0}.number-list{list-style:none;margin:20px 0;padding:0;counter-reset:items}.number-list li{counter-increment:items;position:relative;padding:15px 16px 15px 60px;margin:0 0 12px;background:#fff;border:1px solid var(--line);border-radius:10px}.number-list li::before{content:counter(items,decimal-leading-zero);position:absolute;left:18px;top:14px;color:#048fa9;font-weight:800}.genre-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.genre-card{padding:24px;border:1px solid var(--line);background:#fff;border-radius:12px}.genre-card .genre-tag{font-size:12px;letter-spacing:.1em;color:#078fa5;font-weight:800}.genre-card h3{margin:9px 0}.genre-card p{font-size:14px}.gallery{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:23px}.gallery figure{margin:0;min-width:0;padding:14px 14px 20px;background:#fff;border:1px solid var(--line);border-radius:12px}.gallery figcaption{padding:15px 7px 0;font-size:14px}.gallery figcaption strong{display:block;color:var(--ink);font-size:17px;margin-bottom:6px}.tab-like{display:flex;flex-wrap:wrap;gap:10px;margin-top:22px}.tab-like a{border:1px solid var(--line);background:#fff;border-radius:7px;padding:7px 13px;font-size:13px;font-weight:700}.faq-stack{max-width:830px;border-top:1px solid var(--line)}.faq-item{border-bottom:1px solid var(--line);background:#fff}.faq-item summary{cursor:pointer;position:relative;padding:18px 44px 18px 18px;font-weight:700;color:var(--ink);list-style:none}.faq-item summary::-webkit-details-marker{display:none}.faq-item summary::after{content:'+';position:absolute;right:19px;top:14px;font-size:23px;font-weight:400;color:#0c8ba4}.faq-item[open] 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p{max-width:430px;font-size:14px;color:#c7dfea}.footer-brand{color:#fff;font-weight:800;font-size:24px;display:block;margin-bottom:13px}.footer-brand small{font-size:10px;letter-spacing:.16em;margin-left:5px}.footer-grid h2{color:#fff;font-size:16px}.footer-grid a:not(.footer-brand){display:block;color:#cfe5ef;font-size:14px;margin:9px 0}.footer-grid a:hover{color:#fff;text-decoration:underline}.footer-bottom{padding-block:20px 29px;border-top:1px solid rgba(255,255,255,.16);display:flex;align-items:end;gap:30px;justify-content:space-between}.footer-bottom p{margin:0;max-width:780px;font-size:12px;color:#c2dbe6}.footer-bottom small{font-size:12px;white-space:nowrap;color:#c2dbe6}.back-top{opacity:0;pointer-events:none;position:fixed;right:22px;bottom:23px;z-index:30;border:0;background:var(--navy);color:white;width:42px;height:42px;border-radius:10px;box-shadow:var(--shadow);transition:opacity .2s}.back-top.is-visible{opacity:1;pointer-events:auto}
@media(max-width:1180px){.container{width:calc(100% - 44px)}.nav-row a{padding-inline:9px}.feature-grid{gap:30px}.content-rail{gap:28px}}
@media(max-width:980px){.desktop-nav{display:none}.topbar{min-height:64px;justify-content:space-between;gap:10px}.menu-toggle{display:flex}.brand{margin-right:auto}.brand .media--logo{height:30px;max-width:150px}.brand-caption{display:none}.entry-button{min-height:40px;padding:8px 14px;font-size:13px}.quick-grid{grid-template-columns:1fr;gap:8px}.quick-grid>div{gap:10px}.mobile-drawer{display:block;background:#fff;padding:20px 24px;border-bottom:1px solid var(--line)}.mobile-drawer a{display:block;padding:9px 0;border-bottom:1px solid var(--line);font-weight:600}.drawer-section{font-size:12px;color:#078e9f;font-weight:800;letter-spacing:.12em;margin:18px 0 3px}.drawer-head{display:none}.js .drawer-overlay{display:block;position:fixed;inset:0;background:rgba(10,38,56,.5);z-index:70;visibility:hidden;opacity:0;pointer-events:none;transition:opacity .2s,visibility .2s}.js .mobile-drawer{position:fixed;left:0;top:0;bottom:0;width:min(86vw,344px);z-index:71;visibility:hidden;transform:translateX(-105%);overflow-y:auto;overscroll-behavior:contain;transition:transform .22s,visibility .22s;padding-top:14px;border-right:1px solid var(--line)}.js .drawer-head{display:flex;justify-content:space-between;align-items:center;color:var(--ink);font-weight:800;border-bottom:1px solid var(--line);padding-bottom:8px}.drawer-close{width:40px;height:40px;border:0;background:#eaf6fa;border-radius:7px;font-size:24px;color:var(--ink)}.drawer-open{overflow:hidden}.drawer-open .drawer-overlay{opacity:1;visibility:visible;pointer-events:auto}.drawer-open .mobile-drawer{transform:translateX(0);visibility:visible}.mobile-bottom{display:grid;grid-template-columns:repeat(4,1fr);position:fixed;left:0;right:0;bottom:0;z-index:39;background:#fff;border-top:1px solid var(--line);padding-bottom:env(safe-area-inset-bottom);box-shadow:0 -5px 20px rgba(18,54,83,.05)}.mobile-bottom a{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:56px;font-size:12px;line-height:1.3;gap:4px;color:var(--muted);font-weight:700}.mobile-bottom a span{font-size:19px}.mobile-bottom a[aria-current]{color:var(--blue)}body{padding-bottom:calc(57px + env(safe-area-inset-bottom))}.back-top{bottom:calc(72px + env(safe-area-inset-bottom))}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.content-rail{grid-template-columns:minmax(0,1fr) 215px;gap:20px}}
@media(max-width:760px){.hero{padding-block:38px}.hero-grid,.feature-grid,.feature-grid--reverse,.split-feature,.editor-grid,.content-rail{grid-template-columns:1fr}.hero-grid{gap:25px}.hero-grid .media{order:-1}.feature-grid .media{order:0}.rail-card{position:static}.section{padding-block:34px}.article-section{padding-block:30px}.page-intro{padding-block:35px 28px}.editor-major{padding:22px}.genre-grid,.info-grid,.timeline{grid-template-columns:1fr}.rule-cards{grid-template-columns:1fr}.rule-card p{min-height:0}.reading-steps{grid-template-columns:repeat(2,minmax(0,1fr))}.related-grid{grid-template-columns:1fr}.related-link{min-height:auto}.footer-grid{grid-template-columns:1fr 1fr;gap:22px}.footer-intro{grid-column:1/-1}.footer-bottom{display:block}.footer-bottom small{display:block;margin-top:12px}}
@media(max-width:640px){.container{width:calc(100% - 32px)}body{font-size:15px;line-height:1.8}.hero h1{font-size:30px}.hero p{font-size:15px}.page-intro h1{font-size:27px}.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--banner{height:150px}.media--mobile{height:290px;max-width:250px}.media--inline{height:185px}.media--wide{height:auto;max-height:155px}.gallery{grid-template-columns:1fr}.topic-card{padding:16px}.topic-card h3{font-size:16px}.topic-card p{font-size:13px}.editor-major h3{font-size:21px}.reading-steps{gap:8px}.step{padding:16px}.hero-actions>a{flex:1 1 155px;padding:9px 12px}.quick-links{display:none}.site-footer .footer-grid{padding-block:38px}.entry-button span{display:none}}
@media(max-height:560px) and (max-width:980px){.mobile-bottom{position:static}.back-top{bottom:20px}body{padding-bottom:0}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition-duration:.01ms!important;animation-duration:.01ms!important}}