:root{color-scheme:dark;--bg:#080f1d;--panel:#101b2e;--line:#27344a;--text:#f1f5fd;--muted:#a7b6cb;--blue:#6399ff;--cyan:#66ded6;--gold:#f5c773;--coral:#fc927f}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:30px}body{margin:0;background:var(--bg);color:var(--text);font-family:Inter,"PingFang SC","Microsoft YaHei",sans-serif;line-height:1.65;font-size:16px}button,a,input{touch-action:manipulation}button,a{ -webkit-tap-highlight-color:transparent}button{font:inherit;cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--gold);outline-offset:5px}button{border-radius:8px}a{color:inherit;text-decoration:none}header{height:84px;max-width:1480px;padding:0 48px;margin:auto;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line)}.brand{font-size:20px;font-weight:700;letter-spacing:2px}.brand span{font-weight:400;font-size:14px;color:var(--muted);letter-spacing:0;margin-left:14px}nav{display:flex;gap:30px;font-size:14px;color:#c2cce0}nav a:hover{color:white}.edition,.eyebrow{font-size:12px;letter-spacing:2px;color:var(--blue);font-weight:600}.edition{color:var(--muted)}main{max-width:1480px;margin:auto;padding:0 48px}h1,h2,h3,p{margin:0}h1{font-size:clamp(28px,2.7vw,42px);line-height:1.4;letter-spacing:-1px;font-weight:650}h1 em{font-style:normal;color:#a9c7ff}h2{font-size:30px;line-height:1.4;font-weight:600;letter-spacing:-.6px}h3{font-size:21px;font-weight:600;line-height:1.5}.intro{padding:40px 0 28px;display:flex;gap:20px;justify-content:space-between;align-items:end}.intro .eyebrow{margin-bottom:10px}.intro-note{font-size:14px;color:var(--muted);line-height:1.8}.steps{display:grid;grid-template-columns:repeat(8,1fr);gap:6px;margin-bottom:20px}.steps button{position:relative;text-align:left;background:#101a2b;border:1px solid #27344a;padding:12px 15px;color:var(--muted);transition:.2s}.steps button b{display:block;color:#e3eafb;font-size:19px;line-height:1.35}.steps button span{font-size:14px;white-space:nowrap}.steps button[aria-pressed=true]{background:#244780;border-color:#71a1ff;color:white}.steps button.done{border-top-color:#56769f}.steps button:hover{background:#1b2e4c}.stage-layout{display:grid;grid-template-columns:minmax(0,1.58fr) minmax(300px,1fr);gap:30px;align-items:stretch}.visual-panel{background:radial-gradient(ellipse at 50% 45%,#152747 0,#0c182c 65%);border:1px solid #2b3d56;border-radius:14px;overflow:hidden;display:flex;flex-direction:column}.diagram-top{padding:18px 24px;display:flex;justify-content:space-between;color:#b7c9e6;font-size:14px}.diagram-top #version-chip{background:#243c60;border-radius:5px;font-size:12px;padding:2px 9px;color:#acd1ff}#diagram{width:100%;aspect-ratio:800/365;display:grid;place-items:center}#diagram svg{width:100%;height:auto;max-height:420px;overflow:visible}.legend{display:flex;gap:18px;justify-content:center;flex-wrap:wrap;font-size:14px;color:#c0cee2;padding:6px 15px 16px;min-height:45px}.legend span:before{content:"";display:inline-block;width:9px;height:9px;border-radius:2px;background:var(--c);margin-right:7px}.experiment{padding:14px 24px 16px;border-top:1px solid #273953;min-height:107px;margin-top:auto;display:flex;flex-direction:column;justify-content:center}.experiment p{font-size:14px;color:var(--muted);line-height:1.7}.experiment strong{color:var(--text);font-weight:500}.control-line{display:flex;align-items:center;gap:14px;justify-content:space-between;margin-bottom:8px;flex-wrap:wrap}.control-line label{font-size:14px;color:#cbd9ed;display:flex;gap:10px;align-items:center}.control-line input{width:150px;accent-color:var(--blue)}.mini-buttons{display:flex;gap:7px;flex-wrap:wrap}.mini-buttons button,.control-line button{font-size:14px;padding:6px 13px;border:1px solid #3a526d;background:#142740;color:#d6e5fb}.mini-buttons button[aria-pressed=true],.control-line button.active{background:#204b64;border-color:var(--cyan);color:#bcfff5}.diagram-foot{display:flex;align-items:center;gap:10px;justify-content:space-between;font-size:12px;color:#8197b3;padding:12px 20px;border-top:1px solid #21344f}.text-button{border:0;background:none;color:#bad1f5;padding:0;font-size:12px;white-space:nowrap}.explanation{padding:4px 0 0}.explanation h2{font-size:30px;margin:5px 0 10px}.lead{font-size:17px;color:#d2dded;margin-bottom:18px}.reason{border-left:2px solid #3d4f69;padding-left:16px;margin-bottom:17px}.reason>span,.example>span{font-size:12px;letter-spacing:1px;color:#9bacbf}.reason p{font-size:16px;line-height:1.7;margin-top:4px;color:#d1dced}.reason.change{border-color:var(--blue)}.reason.change>span{color:var(--blue)}.example{background:#131f31;border-radius:8px;padding:13px 17px}.example>span{color:var(--gold)}.example p{font-size:14px;margin-top:3px;line-height:1.75}.source-line{color:#8295ae;font-size:12px;margin-top:12px}.playbar{display:flex;justify-content:space-between;align-items:center;gap:18px;margin-top:20px;border-bottom:1px solid var(--line);padding-bottom:28px}.primary,.secondary{padding:10px 22px;border:1px solid #45689b;background:#689cff;color:#09182c;font-weight:600;white-space:nowrap}.secondary{background:transparent;color:#ccd9ed;border-color:#34445b}.secondary:disabled,.primary:disabled{opacity:.3;cursor:default}.playbar>div{text-align:center;font-size:14px;color:var(--muted)}#step-progress{display:none}#next-question{color:#adc3df}.section{padding:65px 0}.section-heading{margin-bottom:28px}.section-heading h2{margin:9px 0 12px}.section-heading>p:last-child{color:var(--muted)}.chain{display:grid;grid-template-columns:repeat(4,1fr);gap:12px}.chain button{display:flex;gap:15px;align-items:center;text-align:left;border:1px solid var(--line);background:#0d182a;color:#b6c6dd;padding:18px}.chain b{font-size:25px;font-weight:500;color:#72a5ff;min-width:45px}.chain span{font-size:14px}.chain strong{display:block;font-size:16px;color:var(--text);font-weight:500}.chain button:hover{border-color:var(--blue)}.meaning{display:flex;justify-content:space-between;gap:20px;padding-top:25px;font-size:14px;color:var(--muted)}.meaning b{color:#d8e7ff;font-weight:500}.art-section{border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:40px 0;display:grid;grid-template-columns:1fr 1.6fr;align-items:center;gap:40px}.art-section h2{font-size:36px;margin:13px 0 20px}.art-section p{color:var(--muted);margin-bottom:13px}.art-section img{width:100%;border-radius:12px;border:1px solid #243954}.fine{font-size:12px;color:#899eb9;display:block}.image-download{display:inline-block;margin-top:16px;font-size:14px;color:#9bc3ff}.rules-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.rules-grid article{padding:25px;border:1px solid var(--line);background:#0d1828;border-radius:10px;display:flex;flex-direction:column}.rule-num{font-size:21px;color:#7e9bc0;font-variant-numeric:tabular-nums}.rule-num i{font-size:11px;font-style:normal;margin-left:12px;letter-spacing:1px;color:var(--cyan)}.rules-grid h3{margin:12px 0}.rules-grid p{font-size:16px;color:#c3d0e1;flex:1}.rules-grid small{display:block;margin:15px 0 20px;font-size:14px;color:#8fa7c5}.rules-grid button{border:0;background:none;padding:0;text-align:left;color:#a4c7ff;font-size:14px}.rules-grid article.highlight{background:#10223a;border-color:#345379}.use-section{border-top:1px solid var(--line)}.use-section h2{margin:8px 0 28px}.application{display:grid;grid-template-columns:1fr 1.3fr;gap:60px}.application>div{background:#14223a;padding:30px;border-radius:12px}.application>div>span{font-size:12px;color:var(--gold)}.application h3{margin:14px 0}.application p{color:var(--muted)}.application ol{margin:0;padding:0;list-style:none;display:grid;gap:18px}.application li{display:flex;flex-direction:column;border-left:2px solid #304b75;padding-left:18px}.application li b{font-size:16px;font-weight:500;color:#aecdff}.application li span{font-size:14px;color:var(--muted);margin-top:3px}.sources{display:grid;grid-template-columns:1fr 1.8fr;gap:60px;border-top:1px solid var(--line)}.sources h2{margin-top:12px}.sources p{font-size:14px;color:var(--muted);margin-bottom:15px}.sources b{color:#dbe5f6;font-weight:500}.sources details{font-size:14px;border-top:1px solid var(--line);padding-top:16px;color:var(--muted)}summary{cursor:pointer;color:#bbd1f2}footer{max-width:1384px;margin:auto;padding:24px 0 35px;border-top:1px solid var(--line);color:#7e94b1;font-size:12px;display:flex;justify-content:space-between}svg text{font-family:Inter,"PingFang SC","Microsoft YaHei",sans-serif}.flow-dash{stroke-dasharray:9 13;animation:flow 3s linear infinite}@keyframes flow{to{stroke-dashoffset:-88}}.appear{animation:appear .4s ease-out}@keyframes appear{from{opacity:.4;transform:translateY(5px)}to{opacity:1;transform:translateY(0)}}@media(prefers-reduced-motion:reduce){*{animation:none!important;scroll-behavior:auto!important}}@media(min-width:1550px){.explanation{padding-top:15px}}@media(max-width:1100px){header,main{padding-left:28px;padding-right:28px}.intro-note{display:none}.steps button{padding:11px 10px}.steps button span{font-size:12px}.stage-layout{gap:24px;grid-template-columns:1.3fr 1fr}.explanation h2{font-size:25px}.lead{font-size:16px}.reason p{font-size:14px}.explanation .reason{margin-bottom:12px}.rules-grid{grid-template-columns:repeat(2,1fr)}.art-section{grid-template-columns:1fr 1.3fr}.art-section h2{font-size:30px}.art-section p{font-size:14px}footer{margin:0 28px}.diagram-foot{font-size:11px;flex-wrap:wrap}}@media(max-width:760px){header{height:68px;padding:0 20px}.brand{font-size:18px}.brand span{font-size:12px;margin-left:8px}nav{gap:15px;font-size:12px}.edition{display:none}main{padding:0 20px}.intro{padding-top:28px}h1{font-size:28px}.intro .eyebrow{font-size:11px}.steps{grid-template-columns:repeat(4,1fr);gap:7px}.steps button{padding:9px 10px}.steps button b{font-size:18px}.steps button span{font-size:12px}.stage-layout{grid-template-columns:1fr;gap:24px}.diagram-top{padding:14px 16px}#diagram{aspect-ratio:800/390;min-height:180px}.legend{font-size:12px;gap:11px;padding-bottom:10px}.experiment{padding:12px 16px;min-height:105px}.control-line input{width:120px}.diagram-foot{padding:10px 16px}.explanation h2{font-size:28px}.reason p{font-size:16px}.lead{font-size:17px}.example p{font-size:15px}.playbar{align-items:center;gap:12px}.primary,.secondary{padding:9px 14px;font-size:14px}.playbar>div{max-width:170px;font-size:12px}.section{padding:44px 0}.section-heading h2{font-size:25px}.section-heading p{font-size:14px}.chain{grid-template-columns:repeat(2,1fr);gap:8px}.chain button{padding:14px 10px;gap:10px}.chain b{font-size:22px;min-width:35px}.chain strong{font-size:14px}.chain span{font-size:12px}.meaning{flex-direction:column;gap:6px}.art-section{grid-template-columns:1fr;gap:20px}.art-section h2 br{display:none}.art-section h2{font-size:28px}.art-section p{font-size:16px}.rules-grid{grid-template-columns:1fr}.rules-grid article{padding:24px}.application,.sources{grid-template-columns:1fr;gap:25px}.application{gap:30px}.application>div{padding:24px}.sources h2 br{display:none}.sources h2{font-size:25px}footer{margin:0 20px;display:block}footer span{display:block;margin-top:5px}}@media(max-width:390px){nav a:last-child{display:none}.playbar>div{max-width:115px}.control-line{gap:8px}.control-line label{font-size:12px}.steps button{padding:8px}.steps button span{font-size:11px}}
.steps{grid-template-columns:repeat(8,minmax(0,1fr))}.steps button{min-width:0}.steps button span{white-space:normal;display:block;line-height:1.45}.stage-layout>*{min-width:0}.diagram-actions{display:flex;gap:16px;align-items:center}dialog{max-width:min(1100px,96vw);width:1100px;border:1px solid #45648e;border-radius:14px;background:#0c182c;color:#e0eafd;padding:20px}dialog::backdrop{background:#030811d9}dialog .modal-top{display:flex;justify-content:space-between;gap:20px;align-items:center;margin-bottom:20px}dialog .modal-top button{font-size:16px;color:#fff;background:#233957;border:1px solid #45648e;padding:6px 14px}.zoom-scroll{overflow:auto}.zoom-scroll svg{width:100%;min-width:750px;display:block}dialog p{font-size:14px;color:#adc1df;margin-top:15px}@media(max-width:760px){.steps{grid-template-columns:repeat(4,minmax(0,1fr))}.steps button span{min-height:34px;display:flex;align-items:center}.diagram-actions{gap:12px}.diagram-foot{align-items:flex-start}.diagram-foot>span{max-width:50%}.diagram-top{gap:10px}.diagram-top>span:first-child{font-size:12px}.diagram-top #version-chip{white-space:nowrap;height:24px}.zoom-scroll svg{min-width:780px}.control-line label{flex-wrap:wrap}.control-line input{max-width:125px}}
