:root{--bg:#f6fafc;--white:#fff;--wash:#eaf6fa;--wash2:#edf4f8;--cyan:#25c8d1;--sky:#25b6e8;--blue:#1787db;--deep:#174b78;--heading:#183a56;--body:#31485d;--muted:#687d8e;--line:#dce9f0;--footer:#123653;--max:1180px}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:24px}body{margin:0;background:var(--bg);color:var(--body);font:16px/1.8 Arial,"PingFang SC","Microsoft YaHei",sans-serif;overflow-x:hidden}a{color:var(--deep);text-underline-offset:3px}a:hover{color:var(--blue)}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--sky);outline-offset:3px}img{max-width:100%;height:auto}h1,h2,h3,p{margin-top:0}h1,h2,h3{color:var(--heading);line-height:1.38}h1{font-size:clamp(32px,3.5vw,42px);letter-spacing:-.025em}h2{font-size:26px;margin-bottom:18px}h3{font-size:20px;margin-bottom:10px}p{margin-bottom:16px}.shell{width:min(var(--max),calc(100% - 56px));margin-inline:auto}.prose{max-width:780px}.prose p{margin-bottom:19px}.section{padding-block:56px}.section-narrow{padding-block:35px}.eyebrow{font-size:13px;font-weight:800;letter-spacing:.1em;color:#147f9f;text-transform:uppercase}.muted{color:var(--muted)}.lead{font-size:17px;line-height:1.85}.section-intro{max-width:760px}.site-header{position:relative;z-index:30;background:#fff;border-bottom:1px solid var(--line)}.topbar{height:72px;display:flex;align-items:center;gap:20px}.brand{display:flex;align-items:center;text-decoration:none;min-width:160px}.topbar-note{margin-inline:auto;color:var(--muted);font-size:14px;letter-spacing:.12em}.entry-button{display:inline-flex;align-items:center;justify-content:center;gap:10px;background:var(--deep);color:white;text-decoration:none;border-radius:9px;padding:9px 22px;min-height:42px;font-weight:700;white-space:nowrap}.entry-button:hover{background:#12699e;color:#fff}.channel-nav{background:var(--deep)}.channel-inner{display:flex;align-items:stretch;justify-content:space-between;gap:10px;min-height:48px}.channel-inner a{display:flex;align-items:center;padding:10px 12px;color:#eefaff;text-decoration:none;white-space:nowrap;border-bottom:3px solid transparent;font-size:14px}.channel-inner a[aria-current=page]{border-color:#7fe7ed;font-weight:800;color:#fff}.channel-inner a:hover{background:#24618d}.menu-toggle{display:none}.skip-link{position:absolute;top:-60px;left:12px;background:#fff;padding:8px;z-index:99}.skip-link:focus{top:10px}.media{display:flex;align-items:center;justify-content:center;min-width:0;width:100%;overflow:hidden;border-radius:14px;background:var(--wash);border:1px solid var(--line)}.media img{display:block;width:auto;height:auto;max-width:100%;max-height:100%;object-fit:contain;object-position:center}.media--logo{width:auto;max-width:220px;height:38px;background:transparent;border:0;border-radius:0;justify-content:flex-start}.media--logo img{height:auto;max-height:38px;max-width:220px}.media--logo .media-placeholder{padding:0;min-height:0}.brand-fallback{font-size:21px;font-weight:900;color:var(--deep);letter-spacing:.04em;white-space:nowrap}.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:340px;margin-inline:auto}.media--wide{height:auto;min-height:110px;aspect-ratio:3/1}.media-placeholder{width:100%;height:100%;display:flex;justify-content:center;align-items:center}.placeholder-ornament{width:35%;aspect-ratio:1;border-radius:50%;border:16px solid #ccebf2;box-shadow:0 0 0 12px #e4f2f8;opacity:.72}.hero{padding:54px 0 38px;background:linear-gradient(180deg,#edf8fb,transparent)}.hero-grid{display:grid;grid-template-columns:56fr 44fr;gap:45px;align-items:center}.hero h1{margin:10px 0 22px}.hero p{max-width:610px}.cta-links{display:flex;gap:14px;flex-wrap:wrap;margin-top:26px}.button-link{padding:11px 20px;border-radius:8px;background:var(--deep);color:white;text-decoration:none;font-weight:700}.button-link.secondary{background:#fff;border:1px solid #a8cfdf;color:var(--deep)}.button-link:hover{color:#fff;background:var(--blue)}.button-link.secondary:hover{color:var(--deep);background:var(--wash)}.quick-strip{border-block:1px solid var(--line);background:#fff}.quick-inner{display:flex;gap:25px;flex-wrap:wrap;padding-block:13px}.quick-inner div{display:flex;flex-wrap:wrap;align-items:center;gap:12px;font-size:13px}.quick-inner strong{color:var(--heading)}.quick-inner a{text-decoration:none;border-bottom:1px solid #abcada}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:15px;margin-top:25px}.topic-card{display:block;text-decoration:none;background:#fff;border:1px solid var(--line);border-radius:12px;padding:22px;min-width:0;transition:border-color .2s,transform .2s}.topic-card:hover{border-color:#57c6d5;transform:translateY(-2px)}.topic-card strong{display:block;font-size:18px;color:var(--heading);margin-bottom:9px}.topic-card p{font-size:14px;color:var(--muted);line-height:1.7;margin:0}.topic-card .arrow{display:block;color:#1482b2;margin-top:14px}.split-feature{display:grid;grid-template-columns:2fr 1fr;gap:20px}.feature-main,.feature-side article,.paper,.info-card{background:#fff;border:1px solid var(--line);border-radius:14px;padding:25px}.feature-side{display:grid;gap:20px}.feature-main{background:var(--wash)}.feature-main h3{font-size:24px}.feature-side h3{font-size:19px}.feature-main a,.feature-side a{font-weight:700}.editor-grid{display:grid;grid-template-columns:1fr 1fr;align-items:center;gap:44px}.editor-grid.reverse .media{order:-1}.soft-section{background:var(--wash2)}.rule-grid,.three-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.rule-card{padding:25px 24px;background:#fff;border-top:3px solid var(--cyan);border-radius:5px 5px 13px 13px}.rule-card .number{color:#1585b0;font-size:13px;font-weight:800;letter-spacing:.1em}.reading-steps{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;counter-reset:path}.reading-step{padding:18px 20px;border-left:3px solid var(--cyan);background:#fff}.reading-step strong{display:block;color:var(--heading)}.reading-step p{font-size:14px;margin:6px 0 0}.page-heading{padding:42px 0 25px}.page-heading h1{font-size:36px;margin:8px 0 15px}.page-heading p{max-width:860px}.page-layout{display:grid;grid-template-columns:minmax(0,780px) minmax(200px,240px);gap:50px;align-items:start}.page-content{min-width:0}.article-section{margin-block:36px}.article-section h2{padding-bottom:9px;border-bottom:1px solid var(--line)}.article-section h3{margin-top:22px}.aside-box{background:var(--wash);padding:22px;border-radius:12px;position:sticky;top:20px}.aside-box h2{font-size:20px}.aside-box ul{padding-left:19px}.aside-box li{margin:12px 0}.table-wrap{overflow-x:auto;max-width:100%;margin:22px 0;border:1px solid var(--line);border-radius:12px;background:white}.data-table{width:100%;border-collapse:collapse;min-width:560px;font-size:15px}.data-table th,.data-table td{padding:13px 16px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}.data-table th{background:var(--wash);color:var(--heading)}.data-table tr:last-child td{border-bottom:0}.sequence{counter-reset:steps;display:grid;gap:12px}.sequence article{background:#fff;padding:18px 22px;border-left:4px solid var(--cyan)}.sequence h3{margin:0 0 5px}.sequence p{margin:0}.matrix{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.matrix article{background:#fff;padding:22px;border:1px solid var(--line);border-radius:12px}.matrix h3{color:#13759e}.gallery-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:23px}.gallery-grid figure{margin:0;background:#fff;border:1px solid var(--line);padding:14px;border-radius:14px}.gallery-grid figcaption{padding:12px 7px 4px}.gallery-grid figcaption strong{display:block;color:var(--heading)}.gallery-grid figcaption p{margin:8px 0 0;font-size:14px}.jump-links{display:flex;gap:12px;flex-wrap:wrap;padding:14px 0}.jump-links a{display:inline-block;background:#fff;padding:7px 13px;border:1px solid var(--line);border-radius:6px;text-decoration:none}.faq-list{border-top:1px solid var(--line)}.faq-list details{background:#fff;border-bottom:1px solid var(--line);padding:12px 18px}.faq-list summary{cursor:pointer;color:var(--heading);font-weight:700;padding:8px 30px 8px 0}.faq-list details p{padding:4px 0 5px;max-width:800px}.related{border-top:2px solid var(--deep);margin:52px 0 60px;padding-top:22px}.related h2{font-size:23px}.related-links{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.related-links a{background:#fff;border:1px solid var(--line);border-radius:8px;padding:16px;text-decoration:none;font-weight:700}.notice{background:var(--wash);border-left:3px solid var(--cyan);padding:17px 21px;margin:25px 0}.site-footer{background:var(--footer);color:#eaf7ff;padding:47px 0 20px;margin-top:35px}.footer-layout{display:grid;grid-template-columns:1.2fr 1fr;gap:65px}.site-footer strong{font-size:23px}.site-footer strong span{font-size:13px;opacity:.7;margin-left:8px}.site-footer p{max-width:530px}.footer-note{font-size:13px;color:#c7dce8}.site-footer h2{font-size:18px;color:white}.footer-links{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.site-footer a{color:#eaf7ff}.footer-bottom{border-top:1px solid #3b6179;margin-top:28px;padding-top:15px;display:flex;justify-content:space-between;color:#c7dce8;font-size:13px}.mobile-drawer,.drawer-overlay,.mobile-bottom{display:none}@media(max-width:1100px){.topic-grid{grid-template-columns:repeat(3,1fr)}.channel-inner{gap:0}.channel-inner a{padding-inline:8px}}@media(max-width:980px){.shell{width:calc(100% - 44px)}.topbar{height:62px;justify-content:space-between;gap:12px}.topbar-note,.channel-nav{display:none}.menu-toggle{display:flex;flex:0 0 40px;width:40px;height:40px;border:1px solid var(--line);background:#fff;border-radius:8px;flex-direction:column;justify-content:center;align-items:center;gap:4px;cursor:pointer}.menu-toggle span{width:19px;height:2px;background:var(--heading)}.brand{min-width:0;margin-inline:auto;max-width:42%}.media--logo{max-width:175px;height:30px}.media--logo img{max-height:30px;max-width:175px}.brand-fallback{font-size:15px}.entry-button{min-height:40px;padding:7px 12px;font-size:13px}.drawer-overlay{display:block;position:fixed;inset:0;background:rgba(10,31,47,.55);z-index:80;visibility:hidden;opacity:0;pointer-events:none;transition:opacity .2s}.drawer-overlay.is-open{visibility:visible;opacity:1;pointer-events:auto}.mobile-drawer{display:block;position:fixed;inset:0 auto 0 0;width:min(86vw,344px);z-index:81;background:#fff;transform:translateX(-105%);visibility:hidden;transition:transform .22s,visibility .22s;overflow-y:auto;padding:19px 23px;box-shadow:12px 0 30px rgba(0,0,0,.12)}.mobile-drawer.is-open{transform:translateX(0);visibility:visible}.drawer-header{display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--line);padding-bottom:14px}.drawer-close{font-size:30px;background:none;border:0;color:var(--heading);width:40px;height:40px;cursor:pointer}.mobile-drawer nav h2{font-size:13px;color:var(--muted);margin:22px 0 7px}.mobile-drawer nav a{display:block;padding:11px 5px;text-decoration:none;border-bottom:1px solid var(--line);font-weight:700}.drawer-open{overflow:hidden}.mobile-bottom{display:flex;position:fixed;bottom:0;left:0;right:0;z-index:40;justify-content:space-around;background:#fff;border-top:1px solid var(--line);padding:5px 0 max(6px,env(safe-area-inset-bottom))}.mobile-bottom a{padding:6px 13px;text-decoration:none;font-size:13px;font-weight:700}body{padding-bottom:64px}.page-layout{gap:26px;grid-template-columns:minmax(0,1fr) 220px}.hero-grid{gap:22px}.section{padding-block:42px}}@media(max-width:760px){.hero-grid,.editor-grid,.page-layout,.footer-layout,.split-feature{grid-template-columns:1fr}.editor-grid.reverse .media{order:0}.hero-grid .media{order:1}.hero-grid>div:first-child{order:0}.hero{padding:35px 0}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.matrix,.rule-grid,.three-grid{grid-template-columns:1fr}.reading-steps{grid-template-columns:repeat(2,1fr)}.aside-box{position:static}.footer-layout{gap:26px}.related-links{grid-template-columns:1fr}.page-heading h1{font-size:31px}.gallery-grid{grid-template-columns:1fr}.quick-inner{gap:8px 20px}.quick-inner div{width:100%}}@media(max-width:640px){body{font-size:15px;line-height:1.77}.shell{width:calc(100% - 32px)}h1{font-size:29px}h2{font-size:22px}h3{font-size:18px}.lead{font-size:16px}.page-heading h1{font-size:27px}.page-heading{padding:28px 0 12px}.section{padding-block:32px}.topic-grid{grid-template-columns:1fr;gap:10px}.topic-card{padding:17px 18px}.hero h1{font-size:29px}.feature-main,.feature-side article,.paper,.info-card{padding:19px}.media--hero{height:200px}.media--feature{height:180px}.media--card{height:145px}.media--banner{height:150px}.media--mobile{height:290px;max-width:250px}.media--wide{height:auto;min-height:90px}.cta-links{gap:10px}.button-link{font-size:14px}.footer-links{grid-template-columns:repeat(2,1fr)}.footer-bottom{align-items:flex-start;gap:10px;flex-direction:column}.site-footer{margin-top:16px}.table-wrap{margin-inline:-3px}}@media(max-height:440px) and (max-width:980px){.mobile-bottom{position:static}body{padding-bottom:0}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{animation-duration:.01ms!important;transition-duration:.01ms!important}}
