:root{color-scheme:light;--bg:#f6f7f9;--paper:#fff;--ink:#1c293b;--sub:#5f6e7e;--line:#dce2e9;--nav:#112d39;--teal:#087f7a;--soft:#e6f4f0;--orange:#a85c12;--wrong:#b33742;--code:#172635;--code-text:#e7eef5;--radius:16px;font:15px/1.7 "Segoe UI","Microsoft YaHei",system-ui,sans-serif}
*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink)}button,input{font:inherit}a{color:var(--teal);text-underline-offset:4px}button,a,input{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:not-allowed;opacity:.45}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #e6a544;outline-offset:4px}button{border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:9px;padding:9px 15px}button:hover:enabled{background:var(--soft);border-color:var(--teal)}.primary{background:var(--teal);color:white;border-color:var(--teal)}.primary:hover:enabled{background:#086a66;color:white}.ghost{background:transparent}.skip{position:absolute;top:-80px;left:16px;z-index:10;background:var(--paper);padding:12px}.skip:focus{top:8px}.shell{width:100%;margin:0;display:grid;grid-template-columns:250px minmax(0,1fr);align-items:start;min-height:100vh}.rail{min-width:0;background:var(--nav);color:#dce8ec;padding:32px 22px;position:sticky;top:0;height:100vh;overflow-y:auto}.brand{font-weight:750;font-size:21px;letter-spacing:-.5px;line-height:1.2;color:white;text-decoration:none;display:block}.brand small{display:block;font-size:11px;font-weight:500;letter-spacing:2px;margin-top:10px;color:#a6c4cb}.rail .catalog-link{display:block;padding:10px 12px;margin:30px 0 16px;border:1px solid #3e5963;border-radius:9px;color:white;text-decoration:none}.rail h2{font-size:12px;color:#a6c4cb;letter-spacing:1px;font-weight:500;margin:22px 8px 10px}.rail a.chapter{display:flex;gap:9px;padding:8px 10px;border-radius:7px;font-size:12px;text-decoration:none;color:#dce8ec;line-height:1.5;align-items:baseline}.chapter .num{font:11px/1.5 ui-monospace,Consolas,monospace;color:#9eb8c0;min-width:21px}.rail a.chapter:hover{background:#21424e}.rail a.chapter.active{background:#e5f3ef;color:#143e40}.rail .chapter.active .num{color:#326b6a}.rail .chapter.done::after{content:'✓';margin-left:auto;color:#73d3b2}.rail-footer{font-size:11px;color:#a6c4cb;margin:28px 8px 0}.main{padding:32px clamp(24px,3vw,64px) 60px;min-width:0;width:100%;margin:0}.topbar{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-bottom:28px;font-size:13px;color:var(--sub);flex-wrap:wrap}.topbar a{text-decoration:none}.offline{font-size:11px;letter-spacing:1px;border:1px solid var(--line);border-radius:30px;padding:5px 10px;white-space:nowrap}.eyebrow{font:11px/1.6 ui-monospace,Consolas,monospace;letter-spacing:2px;color:var(--teal);text-transform:uppercase}.hero{margin:32px 0 28px}.hero h1{font-size:clamp(28px,3vw,43px);letter-spacing:-1.4px;line-height:1.3;margin:12px 0 16px;font-weight:750}.hero p{color:var(--sub);max-width:700px;margin:0}.hero-top{display:flex;gap:24px;justify-content:space-between;align-items:flex-start}.hero-mark{width:96px;height:96px;border:1px solid #bed9d3;border-radius:22px;display:grid;place-items:center;background:var(--soft);color:var(--teal);font:600 26px ui-monospace,Consolas,monospace;flex:none}.metrics{display:flex;gap:30px;flex-wrap:wrap;font-size:12px;color:var(--sub);margin:24px 0}.metrics b{font-size:20px;color:var(--ink);margin-right:5px}.study-path{display:flex;align-items:center;gap:9px;flex-wrap:wrap;color:var(--sub);font-size:12px;margin:20px 0}.study-path span{background:var(--paper);border:1px solid var(--line);border-radius:7px;padding:6px 10px}.section-head{display:flex;align-items:baseline;gap:10px;flex-wrap:wrap;margin:34px 0 14px}.section-head h2{font-size:21px;margin:0;letter-spacing:-.5px}.section-head .section-no{font:12px ui-monospace,Consolas,monospace;color:var(--teal)}.section-head p{font-size:12px;color:var(--sub);margin:0}.filterbar{display:flex;gap:12px;flex-wrap:wrap;align-items:center;margin:24px 0}.search{border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:10px;padding:10px 14px;min-width:210px;flex:1}.filters{display:flex;gap:5px;flex-wrap:wrap}.filters button{padding:8px 13px;font-size:13px}.filters button[aria-pressed=true]{background:var(--nav);color:white;border-color:var(--nav)}.catalog{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.lesson-card{display:flex;flex-direction:column;min-height:190px;background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:20px;text-decoration:none;color:var(--ink);transition:transform .16s,border-color .16s}.lesson-card:hover{transform:translateY(-3px);border-color:var(--teal)}.lesson-card .card-top{display:flex;justify-content:space-between;gap:8px;font:11px ui-monospace,Consolas,monospace;color:var(--teal)}.lesson-card h3{font-size:17px;line-height:1.5;margin:14px 0 8px}.lesson-card p{font-size:12px;color:var(--sub);margin:0 0 18px}.lesson-card .card-bottom{font-size:11px;color:var(--sub);margin-top:auto;display:flex;justify-content:space-between}.empty{padding:30px;text-align:center;color:var(--sub);grid-column:1/-1}.progress-line{height:5px;overflow:hidden;background:var(--line);border-radius:10px;margin:10px 0}.progress-line span{display:block;height:100%;background:var(--teal);transition:width .2s}.prereq{font-size:12px;color:var(--sub);display:flex;gap:8px;flex-wrap:wrap;margin:18px 0}.prereq a{padding:3px 9px;border:1px solid var(--line);border-radius:6px;background:var(--paper);text-decoration:none}.concepts{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.concept{padding:20px;background:var(--paper);border:1px solid var(--line);border-radius:12px;font-size:13px}.concept .point-no{font:11px ui-monospace,Consolas,monospace;color:var(--teal);display:block;margin-bottom:10px}.outline{border:1px solid var(--line);background:var(--paper);border-radius:12px;margin:16px 0;padding:15px 20px}.outline summary{cursor:pointer;font-size:13px;font-weight:600}.outline ul{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px 22px;padding-left:20px;font-size:12px;color:var(--sub)}.lab{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden}.lab-header{padding:16px 22px;border-bottom:1px solid var(--line);display:flex;gap:15px;justify-content:space-between;align-items:center;flex-wrap:wrap}.lab-label{font-size:12px;color:var(--sub)}.lab-label strong{color:var(--ink);font-weight:600}.steps{display:flex;gap:7px;flex-wrap:wrap}.step-dot{border:0;background:#e9edf1;border-radius:50%;padding:0;width:29px;height:29px;font:12px ui-monospace,Consolas,monospace}.step-dot[aria-current=step]{background:var(--teal);color:white}.step-dot.visited{box-shadow:inset 0 0 0 1px #9ac8bd}.lab-body{display:grid;grid-template-columns:minmax(0,.8fr) minmax(0,1.2fr);min-height:350px}.code-side{padding:20px;background:var(--code);color:var(--code-text);min-width:0}.code-caption{color:#91b4c3;font:11px ui-monospace,Consolas,monospace;letter-spacing:1px;margin-bottom:18px}.code-side pre{white-space:pre-wrap;overflow-wrap:anywhere;font:13px/1.9 ui-monospace,Consolas,"Microsoft YaHei",monospace;margin:0}.code-side .code-comment{color:#aac6b9}.visual-side{min-width:0;padding:20px}.scene-caption{font-size:11px;color:var(--sub);display:flex;justify-content:space-between;gap:10px;margin-bottom:15px}.scene{position:relative;padding:12px 0;min-height:235px}.scene-links{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;z-index:0;overflow:visible}.scene-links path{stroke:var(--teal);stroke-width:1.6;fill:none}.scene-links marker path{fill:var(--teal);stroke:none}.nodes{position:relative;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:40px 28px}.visual-node{position:relative;z-index:1;background:var(--paper);border:1px solid #ced9e0;border-radius:10px;padding:12px 14px;min-width:0;transition:background .2s,border-color .2s}.visual-node.active{background:var(--soft);border-color:#67a99a;box-shadow:0 0 0 3px #e6f4f0}.node-label{font-size:11px;color:var(--sub);overflow-wrap:anywhere}.node-value{font-size:17px;line-height:1.5;font-weight:600;margin:6px 0;overflow-wrap:anywhere;white-space:pre-wrap}.node-note{font-size:11px;color:var(--sub);overflow-wrap:anywhere}.scene.array .nodes{display:flex;flex-wrap:wrap;gap:10px}.scene.array .visual-node{flex:1 1 85px}.scene.array .node-value{text-align:center;font-family:ui-monospace,Consolas,monospace}.scene.stack .nodes{display:flex;flex-direction:column-reverse;gap:10px}.scene.stack .visual-node{display:grid;grid-template-columns:minmax(80px,.8fr) minmax(0,1fr);align-items:center;gap:12px;border-left:4px solid #c7d6e2}.scene.stack .visual-node.active{border-left-color:var(--teal)}.scene.stack .node-value{font-size:14px;margin:0}.scene.lanes .nodes{grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}.scene.lanes .visual-node{min-height:145px}.scene.layout .nodes{display:flex;gap:12px;flex-wrap:wrap;align-items:stretch}.scene.layout .visual-node{flex:1 1 110px}.scene.layout .visual-node:nth-child(2){flex-grow:2}.scene.table .nodes{display:flex;flex-direction:column;gap:0;border:1px solid var(--line);border-radius:10px;overflow:hidden}.scene.table .visual-node{border:0;border-bottom:1px solid var(--line);border-radius:0;display:grid;grid-template-columns:1fr 1fr;align-items:center;gap:10px}.scene.table .visual-node:last-child{border-bottom:0}.scene.table .node-value{margin:0}.scene.ui .visual-node{border-top:3px solid #c8d9df}.scene.ui .visual-node.active{border-top-color:var(--teal)}.explain{background:#f0f6f5;border-top:1px solid #d6e7e2;padding:17px 22px;display:flex;gap:14px;font-size:13px}.explain-label{color:var(--teal);white-space:nowrap;font-weight:600}.lab-controls{padding:15px 22px;display:flex;gap:8px;align-items:center;flex-wrap:wrap}.lab-controls .step-count{margin-left:auto;color:var(--sub);font:12px ui-monospace,Consolas,monospace}.simulation-note{font-size:11px;color:var(--sub);margin:10px 2px}.pitfalls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.pitfall{padding:17px 20px;background:#fff8ee;border:1px solid #eedfc5;border-radius:12px;font-size:13px}.pitfall strong{display:block;color:var(--orange);font-size:11px;margin-bottom:6px}.quiz-box,.practice{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:22px}.quiz-box fieldset{border:0;padding:0;margin:0 0 15px;min-width:0}.quiz-box legend{font-weight:600;font-size:15px;margin-bottom:14px}.choices{display:grid;gap:8px}.choice{display:flex;gap:10px;align-items:flex-start;border:1px solid var(--line);border-radius:8px;padding:11px 13px;cursor:pointer;font-size:13px}.choice:hover{background:var(--bg)}.choice input{margin-top:5px;accent-color:var(--teal)}.quiz-result{margin-top:14px;font-size:13px;padding:12px 15px;background:var(--soft);border-radius:8px}.quiz-result.wrong{background:#fff0f1;color:#8e2e37}.practice p{margin:0 0 16px;font-size:14px}.checkline{display:flex;gap:10px;align-items:flex-start;font-size:13px;color:var(--sub)}.checkline input{margin-top:6px;accent-color:var(--teal)}.resources{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;margin:18px 0}.resources h3{font-size:13px;margin:0 0 10px}.resources a{display:block;font:11px/1.6 ui-monospace,Consolas,"Microsoft YaHei",monospace;overflow-wrap:anywhere;margin:6px 0}.resources .more-links{font-size:12px}.source-reader{background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:18px 22px;margin:20px 0;font-size:13px;overflow-wrap:anywhere}.source-reader summary{cursor:pointer;font-weight:600}.source-reader h2,.source-reader h3{font-size:19px}.source-reader h4,.source-reader h5{font-size:16px}.source-reader pre{background:var(--code);color:var(--code-text);padding:16px;border-radius:9px;white-space:pre-wrap;overflow-wrap:anywhere;font:12px/1.8 ui-monospace,Consolas,monospace}.source-note{border-left:3px solid #b5d3c8;padding-left:12px;color:var(--sub)}.table-scroll{max-width:100%;overflow-x:auto}table{width:100%;border-collapse:collapse;font-size:12px}th,td{border:1px solid var(--line);padding:8px;text-align:left}th{background:var(--bg)}.completion{display:flex;justify-content:space-between;align-items:center;gap:15px;flex-wrap:wrap;padding:20px 0;border-top:1px solid var(--line);margin-top:26px}.completion p{font-size:12px;color:var(--sub);margin:4px 0}.completion strong{font-size:14px}.lesson-nav{display:flex;justify-content:space-between;gap:15px;margin:30px 0 0}.lesson-nav a{text-decoration:none;border:1px solid var(--line);padding:12px 16px;border-radius:10px;background:var(--paper);font-size:12px;max-width:48%}.footer{margin-top:40px;padding-top:16px;border-top:1px solid var(--line);color:var(--sub);font-size:11px}.status-banner{padding:12px 16px;border-radius:10px;background:#fff8ee;font-size:12px;color:#775326;margin-bottom:16px}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}

@media(max-width:1200px){.main{padding:28px}.catalog{grid-template-columns:repeat(2,minmax(0,1fr))}.shell{grid-template-columns:220px minmax(0,1fr)}.rail{padding:28px 16px}.lab-body{grid-template-columns:1fr}.code-side{min-height:140px}.scene{min-height:210px}.concepts{grid-template-columns:1fr}.concept{padding:15px 18px}.concept .point-no{display:inline;margin-right:10px}.scene.lanes .nodes{gap:18px}}
@media(max-width:760px){.shell{display:block}.rail{position:static;height:auto;overflow:visible;padding:16px 20px;display:flex;justify-content:space-between;align-items:center;gap:12px}.rail .brand{font-size:18px}.rail .brand small{font-size:9px;margin-top:5px}.rail .catalog-link{margin:0;padding:6px 10px;font-size:12px}.rail nav,.rail-footer{display:none}.main{padding:20px}.topbar{margin-bottom:24px}.hero{margin-top:20px}.hero-mark{display:none}.hero h1{font-size:29px}.catalog{grid-template-columns:repeat(2,minmax(0,1fr))}.lesson-card{padding:17px;min-height:180px}.lesson-card h3{font-size:15px}.pitfalls,.resources{grid-template-columns:1fr}.outline ul{grid-template-columns:1fr}.metrics{gap:20px}.lab-header,.lab-controls{padding:14px 16px}.visual-side,.code-side{padding:16px}.explain{padding:15px 16px;display:block}.explain-label{display:block;margin-bottom:6px}.quiz-box,.practice{padding:18px}.scene.lanes .nodes{grid-template-columns:1fr;gap:30px}.scene.lanes .visual-node{min-height:auto}.scene.stack .visual-node{grid-template-columns:1fr}.node-value{font-size:16px}}
@media(max-width:420px){.main{padding:16px}.catalog{grid-template-columns:1fr}.lesson-card{min-height:145px}.search{width:100%;min-width:0}.filters{width:100%}.filters button{flex:1;padding:8px}.lab-controls button{padding:8px 11px}.lab-controls .step-count{width:100%;margin:2px 0 0}.nodes{gap:36px 16px}.visual-node{padding:10px}.node-value{font-size:14px}.scene-caption{flex-wrap:wrap}.hero h1{font-size:26px}.topbar{font-size:11px}.offline{font-size:9px}.lesson-nav{flex-direction:column}.lesson-nav a{max-width:100%}.completion .primary{width:100%}.step-dot{width:27px;height:27px}.quiz-box legend{font-size:14px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
@media print{.rail,.topbar,.lab-controls,.steps,.completion,.lesson-nav,.filters{display:none!important}.shell{display:block}.main{padding:0}.lab,.concept,.pitfall{break-inside:avoid}.source-reader:not([open]){display:none}.code-side{-webkit-print-color-adjust:exact;print-color-adjust:exact}}