:root{--bg:#F6FAFC;--white:#fff;--soft:#EAF6FA;--soft2:#EDF4F8;--cyan:#25C8D1;--sky:#25B6E8;--blue:#1787DB;--deep:#174B78;--heading:#183A56;--body:#31485D;--muted:#687D8E;--line:#DCE9F0;--footer:#123653;--width:1180px;--radius:16px}
*,*::before,*::after{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:30px}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}a{color:var(--deep);text-underline-offset:4px}a:hover{color:var(--blue)}:focus-visible{outline:3px solid var(--blue);outline-offset:3px}button{font:inherit;cursor:pointer}img{display:block;max-width:100%}.container{width:min(calc(100% - 56px),var(--width));margin-inline:auto}.section{margin-block:56px}.section-head{max-width:780px;margin-bottom:25px}.section-head h2{margin:4px 0 12px}h1,h2,h3{color:var(--heading);line-height:1.38;letter-spacing:-.015em}h1{font-size:clamp(32px,3.2vw,40px);margin:12px 0 22px}h2{font-size:clamp(24px,2.5vw,27px);margin:0 0 17px}h3{font-size:19px;margin:0 0 12px}p{margin:0 0 18px}strong{font-weight:700}.eyebrow{color:#087caa;font-size:13px;letter-spacing:.13em;font-weight:700;text-transform:uppercase;margin:0 0 6px}.lead{font-size:17px;line-height:1.83;color:#425c70}.muted{color:var(--muted)}.skip-link{position:absolute;left:12px;top:-70px;z-index:300;padding:9px 14px;background:white}.skip-link:focus{top:8px}.site-header{background:var(--white);border-bottom:1px solid var(--line);position:relative;z-index:30}.topbar{height:72px;display:flex;align-items:center;gap:24px}.brand{display:flex;align-items:center;text-decoration:none;color:var(--heading);font-size:23px;white-space:nowrap}.brand-en{font-size:11px;letter-spacing:.05em;color:var(--muted)}.brand-tagline{margin:auto;color:var(--muted);font-size:14px}.top-cta,.button-primary{background:var(--deep);color:white!important;text-decoration:none;border-radius:9px;padding:9px 22px;display:inline-flex;justify-content:center;align-items:center;font-weight:700;min-height:42px;transition:background .2s}.top-cta:hover,.button-primary:hover{background:#0c74b6}.button-outline{border:1px solid #7daac6;border-radius:9px;padding:9px 18px;display:inline-flex;text-decoration:none;font-weight:700;min-height:42px;align-items:center}.desktop-nav{background:var(--deep)}.nav-inner{min-height:48px;display:flex;justify-content:space-between;gap:14px}.desktop-nav a{display:flex;align-items:center;white-space:nowrap;font-size:14px;font-weight:700;color:#e7f6fd;text-decoration:none;border-bottom:3px solid transparent;padding:3px 8px 0}.desktop-nav a:hover,.desktop-nav a[aria-current]{color:white;border-bottom-color:var(--cyan)}.menu-toggle{display:none}.mobile-drawer,.drawer-shade{display:none}.media{display:flex;align-items:center;justify-content:center;min-width:0;width:100%;overflow:hidden;border-radius:14px;background:var(--soft);position:relative}.media img{display:block;width:auto;height:auto;max-width:100%;max-height:100%;object-fit:contain;object-position:center}.media-placeholder{width:56%;height:42%;border-radius:12px;border:1px solid #d4e8ef;background:linear-gradient(145deg,#e3f1f7,#f3fbfd)}.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;margin-inline:auto}.media--portrait{max-width:370px;margin-inline:auto}.media--wide{background:#f5fbfc}.media--logo{height:38px;width:auto;border-radius:0;background:transparent;overflow:visible}.media--logo img{height:100%;width:auto;max-width:240px}.quick-path{background:#eaf6fa;border-bottom:1px solid var(--line)}.quick-path .container{display:flex;justify-content:space-between;gap:12px;padding-block:12px}.quick-path div{display:flex;gap:10px;flex-wrap:wrap;font-size:13px}.quick-path strong{color:var(--heading)}.quick-path a{font-weight:600;text-decoration:none}.hero{display:grid;grid-template-columns:minmax(0,1.12fr) minmax(0,.88fr);gap:42px;align-items:center;margin-block:50px 58px}.hero-copy p{max-width:630px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:24px}.hero .media{border:1px solid var(--line)}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.topic-card{display:flex;flex-direction:column;gap:8px;padding:22px;background:white;border:1px solid var(--line);border-radius:14px;text-decoration:none;min-height:180px;transition:transform .2s,border-color .2s}.topic-card:hover{transform:translateY(-3px);border-color:#8dcbd8}.topic-card strong{font-size:18px;color:var(--heading)}.topic-card span{color:var(--muted);font-size:14px;line-height:1.7}.topic-card i{margin-top:auto;font-style:normal;font-size:15px;color:var(--blue)}.editor-picks{display:grid;grid-template-columns:1.8fr 1fr;gap:18px}.feature-essay{padding:30px;border-radius:16px;background:var(--soft);border:1px solid #d7ebf1}.feature-essay h3{font-size:23px}.feature-essay p:last-child{margin-bottom:0}.pick-stack{display:grid;gap:18px}.pick-item{background:white;padding:24px;border-radius:14px;border:1px solid var(--line)}.pick-item p{font-size:15px}.text-link{font-weight:700;color:#087eaa;text-decoration:underline;text-underline-offset:5px}.alternating{display:grid;grid-template-columns:1fr 1fr;gap:38px;align-items:center}.alternating.reverse .media{order:-1}.kicker-list{display:flex;gap:14px;flex-wrap:wrap;margin:18px 0 0}.kicker-list span{padding:5px 12px;border:1px solid var(--line);border-radius:7px;background:#fff;font-size:13px}.culture-feature{padding:28px;border:1px solid var(--line);border-radius:16px;background:white}.rules-cards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:17px}.rule-card{padding:26px;border-left:4px solid var(--cyan);background:var(--soft2);border-radius:0 12px 12px 0}.rule-card h3{font-size:18px}.rule-card p{font-size:15px}.reading-path{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;list-style:none;margin:0;padding:0;counter-reset:reading}.reading-path li{counter-increment:reading;border-top:2px solid var(--cyan);padding:15px 8px 0}.reading-path li:before{content:'0' counter(reading);display:block;color:#168bae;font-weight:700;font-size:14px;margin-bottom:8px}.editor-note{background:#e7f2f6;border-radius:12px;padding:22px 26px;font-size:14px}.editor-note p:last-child{margin:0}.page-intro{padding-top:48px;max-width:830px}.page-intro h1{font-size:clamp(30px,3vw,35px)}.page-intro .lead{margin-bottom:15px}.content-panel{padding:30px;border:1px solid var(--line);border-radius:15px;background:white}.prose{max-width:780px}.prose h2{margin-top:36px}.prose h2:first-child{margin-top:0}.content-panel p:last-child{margin-bottom:0}.section-copy{max-width:780px}.split{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(0,.8fr);gap:32px;align-items:center}.wide-prose{max-width:820px}.columns-2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:24px}.columns-3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.info-tile{background:white;border:1px solid var(--line);border-radius:12px;padding:22px}.info-tile p:last-child{margin:0}.table-scroll{overflow-x:auto;background:white;border:1px solid var(--line);border-radius:12px}.data-table{width:100%;border-collapse:collapse;min-width:600px;font-size:15px}.data-table th,.data-table td{padding:14px 17px;text-align:left;vertical-align:top;border-bottom:1px solid var(--line)}.data-table tr:last-child td{border:0}.data-table th{background:var(--soft);font-weight:700;color:var(--heading)}.data-table th[scope=row]{background:#f6fafc}.timeline,.steps{list-style:none;padding:0;margin:0;counter-reset:step}.timeline li,.steps li{position:relative;padding:0 0 28px 52px;border-left:2px solid #9bcfd9;margin-left:15px}.timeline li:last-child,.steps li:last-child{padding-bottom:0;border-left-color:transparent}.timeline li:before,.steps li:before{counter-increment:step;content:counter(step);position:absolute;left:-17px;top:0;display:grid;place-items:center;width:32px;height:32px;border-radius:50%;background:var(--deep);color:white;font-weight:700;font-size:13px}.timeline strong,.steps strong{display:block;font-size:18px;color:var(--heading)}.timeline p,.steps p{margin:5px 0 0}.aside-layout{display:grid;grid-template-columns:minmax(0,760px) minmax(210px,240px);gap:45px;justify-content:space-between}.term-aside{align-self:start;position:sticky;top:25px;background:var(--soft);padding:23px;border-radius:13px}.term-aside dl{margin:0}.term-aside dt{font-weight:700;color:var(--heading);margin-top:15px}.term-aside dd{margin:0;color:var(--muted);font-size:14px}.anchor-index{display:flex;gap:12px;flex-wrap:wrap;margin:21px 0}.anchor-index a{display:inline-flex;padding:7px 12px;background:#e3f2f7;border-radius:7px;font-size:14px;text-decoration:none;font-weight:700}.topic-number{font-weight:700;color:#1589ae;margin:0 0 7px}.gallery-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px}.gallery-item{background:white;border:1px solid var(--line);border-radius:15px;padding:16px}.gallery-item h3,.gallery-item p{margin-left:5px;margin-right:5px}.gallery-item h3{margin-top:16px}.gallery-item p{font-size:14px}.faq-list{max-width:900px}.faq-list details{background:white;border:1px solid var(--line);border-radius:10px;padding:16px 19px;margin-bottom:10px}.faq-list summary{cursor:pointer;font-weight:700;color:var(--heading);line-height:1.5}.faq-list details p{margin:13px 0 0;font-size:15px}.related-list{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.related-link{border:1px solid var(--line);background:white;border-radius:10px;padding:18px;display:flex;align-items:center;justify-content:space-between;gap:10px;text-decoration:none;font-weight:700}.related-link span:last-child{color:#118cad}.site-footer{background:var(--footer);color:#eaf7ff;margin-top:70px}.footer-grid{display:grid;grid-template-columns:1.3fr 1fr;gap:70px;padding-block:42px}.footer-brand{color:white;text-decoration:none;font-weight:700;font-size:22px}.footer-brand small{display:block;letter-spacing:.1em;font-size:11px;color:#b8d9e8}.footer-grid p{font-size:14px;margin-top:10px;color:#d0e6f1}.footer-note{max-width:590px}.footer-links{display:grid;grid-template-columns:repeat(2,1fr);gap:7px 18px;margin-top:12px}.site-footer a{color:#eaf7ff}.site-footer nav strong{font-size:16px}.footer-bottom{border-top:1px solid #3d607b;padding-block:15px;display:flex;justify-content:space-between;gap:20px;font-size:12px;color:#c5dfed}.bottom-nav{display:none}.back-to-top{position:fixed;right:22px;bottom:23px;z-index:15;border:1px solid #bdd9e5;background:white;color:var(--deep);width:44px;height:44px;border-radius:12px;font-size:22px;opacity:0;visibility:hidden;transition:opacity .2s}.back-to-top.visible{opacity:1;visibility:visible}
@media(max-width:1100px){.topic-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.quick-path .container{flex-wrap:wrap}.desktop-nav a{font-size:13px;padding-inline:4px}}
@media(max-width:980px){.container{width:calc(100% - 44px)}.topbar{height:64px;justify-content:space-between;gap:12px}.brand{margin:auto}.brand-tagline,.desktop-nav{display:none}.top-cta{font-size:13px;padding:7px 11px;min-height:40px;white-space:nowrap}.menu-toggle{width:40px;height:40px;border:1px solid var(--line);border-radius:9px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;background:white;flex-shrink:0}.menu-toggle span{width:19px;height:2px;border-radius:2px;background:var(--deep)}.drawer-shade{display:block;position:fixed;inset:0;background:rgba(11,31,47,.52);z-index:80;visibility:hidden;opacity:0;pointer-events:none;transition:opacity .22s,visibility .22s}.mobile-drawer{display:block;position:fixed;inset:0 auto 0 0;width:min(86vw,344px);z-index:81;background:white;transform:translateX(-101%);transition:transform .22s;overflow-y:auto;overscroll-behavior:contain;padding:20px 22px 50px;visibility:hidden}.drawer-open .drawer-shade{opacity:1;visibility:visible;pointer-events:auto}.drawer-open .mobile-drawer{transform:translateX(0);visibility:visible}.drawer-heading{display:flex;justify-content:space-between;align-items:center;padding-bottom:10px;border-bottom:1px solid var(--line);color:var(--heading)}.drawer-close{font-size:28px;line-height:1;border:0;background:transparent;color:var(--deep);width:42px;height:42px}.drawer-title{font-weight:700;color:var(--muted);font-size:12px;margin:20px 0 4px}.mobile-drawer a{display:block;padding:10px 8px;border-bottom:1px solid var(--line);text-decoration:none;font-weight:600}.hero{gap:26px}.aside-layout{grid-template-columns:minmax(0,1fr) 210px;gap:25px}}
@media(max-width:760px){.section{margin-block:35px}.hero,.split,.alternating,.editor-picks,.aside-layout,.footer-grid{grid-template-columns:1fr}.hero{margin-block:28px 38px}.hero .media{order:-1}.hero h1{font-size:30px}.alternating.reverse .media{order:0}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.rules-cards,.related-list{grid-template-columns:1fr}.reading-path{grid-template-columns:repeat(2,1fr)}.term-aside{position:static}.footer-grid{gap:26px}.page-intro{padding-top:32px}.columns-3{grid-template-columns:1fr 1fr}}
@media(max-width:640px){body{font-size:15px}.container{width:calc(100% - 32px)}.topbar{height:62px}.brand{font-size:17px}.brand-en{display:none}.media--logo{height:29px}.media--logo img{max-width:165px}.hero h1{font-size:28px}.page-intro h1{font-size:26px}.lead{font-size:15px}.section-head h2,h2{font-size:21px}h3{font-size:18px}.hero .media--hero,.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--banner{height:150px}.media--mobile{height:290px;max-width:250px}.media--portrait{max-width:245px}.quick-path .container{gap:5px;padding-block:9px}.quick-path div{font-size:12px;gap:6px 10px}.quick-path strong{width:100%}.topic-grid,.columns-2,.columns-3,.gallery-grid{grid-template-columns:1fr}.topic-card{min-height:0;padding:18px}.feature-essay,.content-panel,.culture-feature{padding:20px}.pick-item,.info-tile,.rule-card{padding:20px}.reading-path li{font-size:14px}.footer-bottom{flex-wrap:wrap}.bottom-nav{position:fixed;z-index:18;bottom:0;left:0;right:0;display:grid;grid-template-columns:repeat(4,1fr);background:white;border-top:1px solid var(--line);padding-bottom:env(safe-area-inset-bottom);box-shadow:0 -2px 12px rgba(15,46,67,.05)}.bottom-nav a{text-decoration:none;min-height:50px;display:flex;align-items:center;justify-content:center;font-size:13px;font-weight:700}.bottom-nav a[aria-current]{color:var(--blue);box-shadow:inset 0 3px var(--cyan)}body{padding-bottom:calc(50px + env(safe-area-inset-bottom))}.back-to-top{bottom:calc(68px + env(safe-area-inset-bottom));right:12px}.site-footer{margin-top:40px}.hero-actions{flex-direction:column;align-items:stretch}.hero-actions a{text-align:center}.data-table{font-size:13px}.data-table td,.data-table th{padding:10px 12px}}
@media(max-height:460px) and (max-width:640px){.bottom-nav{position:static}body{padding-bottom:0}.back-to-top{bottom:15px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}