:root{--bg:#F6F8F8;--white:#fff;--pale:#EAF0F2;--nav:#122E3B;--dark:#1A4050;--teal:#168E96;--link:#226D9D;--head:#193946;--body:#374D58;--muted:#647981;--line:#D9E3E6;--footer:#0C2632}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:100px}body{margin:0;background:var(--bg);color:var(--body);font:16px/1.8 Arial,'PingFang SC','Microsoft YaHei',sans-serif}a{color:var(--link);text-underline-offset:3px}a:hover{color:var(--teal)}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid #2cb5bc;outline-offset:3px}img{max-width:100%;height:auto}h1,h2,h3{color:var(--head);line-height:1.35}h1{font-size:clamp(26px,3.2vw,42px);letter-spacing:-.025em;margin:0 0 22px}h2{font-size:clamp(21px,2.2vw,28px);margin:0 0 17px}h3{font-size:20px;margin:0 0 10px}p{margin:0 0 16px}ul,ol{padding-left:1.45em}li{margin:0 0 9px}section{margin-block:50px}section[id]{scroll-margin-top:100px}.wrap{max-width:1220px;margin-inline:auto;padding-inline:28px}.skip{position:absolute;left:-999px;top:8px;background:white;color:var(--head);padding:8px;z-index:20}.skip:focus{left:8px}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0)}
.site-header{background:var(--nav);color:white;position:relative;z-index:10}.header-inner{max-width:1220px;padding:0 28px;margin:auto;min-height:76px;display:flex;align-items:center;gap:20px}.brand{display:flex;align-items:center;flex-shrink:0;gap:8px;color:white;text-decoration:none}.brand:hover{color:white}.brand-logo{display:flex;max-width:135px}.brand-wordmark{font-size:10px;letter-spacing:.09em;line-height:1.2;white-space:nowrap}.desktop-nav{display:flex;justify-content:center;flex:1;min-width:0;align-items:center;gap:clamp(8px,1vw,18px)}.desktop-nav a{color:#ebf3f4;text-decoration:none;font-size:13px;white-space:nowrap;border-bottom:2px solid transparent;padding:7px 0}.desktop-nav a:hover,.desktop-nav a.is-active{border-color:#49bec1;color:white;font-weight:700}.register-link{white-space:nowrap;background:#fff;color:var(--nav);padding:7px 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var(--line)}.topic-group a{display:block;padding:18px 24px 18px 0;text-decoration:none}.topic-group a+a{padding-left:24px;border-left:1px solid var(--line)}.topic-group small{display:block;color:var(--teal);font-weight:700}.topic-group strong{display:block;color:var(--head);font-size:19px}.topic-group p{color:var(--body);margin:4px 0 0}.image-holder{display:flex;flex-direction:column;align-items:center;justify-content:center;width:100%;min-width:0;padding:8px;background:var(--pale);border-radius:12px;margin:0}.image-holder img{display:block;width:auto;height:auto;max-width:100%;max-height:var(--image-limit,210px);object-fit:contain;object-position:center}.image-holder figcaption{font-size:13px;color:var(--muted);text-align:center;padding:8px 5px 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@media(max-width:1200px){.wrap,.header-inner{padding-inline:22px}.header-inner{gap:12px}.desktop-nav{gap:9px}.desktop-nav a{font-size:12px}.brand-wordmark{font-size:9px}}@media(max-width:980px){.header-inner{height:64px;min-height:64px;justify-content:space-between}.desktop-nav{display:none}.mobile-nav{display:block;order:0}.brand{order:1}.register-link{order:2}.mobile-nav summary{cursor:pointer;list-style:none;color:white;display:flex;align-items:center;justify-content:center;width:42px;height:42px;font-size:22px}.mobile-nav summary::-webkit-details-marker{display:none}.mobile-nav-panel{position:absolute;left:0;right:0;top:100%;background:#fff;color:var(--head);padding:18px max(22px,calc((100vw - 1176px)/2));box-shadow:0 12px 23px #122e3b1f;border-bottom:1px solid var(--line)}.mobile-nav-title{display:flex;justify-content:space-between;align-items:center;padding-bottom:12px}.menu-close{background:var(--pale);border:1px solid var(--line);color:var(--head);padding:8px 12px;border-radius:6px;cursor:pointer}.mobile-nav-groups{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.mobile-nav-groups span{display:block;color:var(--muted);font-size:12px;border-bottom:1px solid var(--line)}.mobile-nav-groups a{display:block;text-decoration:none;padding:7px 0;color:var(--head)}.mobile-nav-groups a.is-active{font-weight:700;color:var(--teal)}.brand-logo .image-holder img{max-height:30px}.image-holder--logo{--image-limit:30px}}
@media(max-width:760px){.split,.split--wide,.split--reverse,.three-cols,.two-cols,.article-grid{grid-template-columns:minmax(0,1fr)}.side-index{position:static;display:flex;gap:14px;flex-wrap:wrap}.article-body{max-width:none}.split{gap:20px}.mobile-nav-groups{grid-template-columns:1fr;gap:10px}.mobile-nav-groups>div{display:flex;flex-wrap:wrap;gap:8px 18px}.mobile-nav-groups span{width:100%}.mobile-nav-panel{max-height:calc(100vh - 64px);overflow:auto}.topic-group{grid-template-columns:1fr}.topic-group a+a{padding-left:0;border-left:0;border-top:1px solid var(--line)}}
@media(max-width:640px){body{font-size:15px;line-height:1.76}.wrap{padding-inline:16px}.header-inner{padding-inline:16px}.brand-wordmark{font-size:9px}.brand-logo{max-width:105px}h1{font-size:28px}h2{font-size:22px}.lede{font-size:16px}section{margin-block:34px}.surface,.pale,.dark-panel{padding:18px}.image-holder--hero{--image-limit:195px}.image-holder--feature{--image-limit:180px}.image-holder--inline{--image-limit:140px}.image-holder--rules{--image-limit:165px}.image-holder--banner{--image-limit:125px}.image-holder--portrait{--image-limit:275px;max-width:240px}.related{margin-top:36px}.crumbs{padding-block:11px}.register-link{padding:7px 9px;font-size:12px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{animation-duration:.01ms!important;transition-duration:.01ms!important}}
