:root{--ink:#172c49;--muted:#52657d;--blue:#215bea;--light:#eaf0ff;--orange:#d76c13;--line:#dce4ef;--paper:#f4f7fc;--mono:ui-monospace,SFMono-Regular,Consolas,monospace}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:Inter,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:18px;line-height:1.5}button,input,select{font:inherit}button,a,input,select{touch-action:manipulation}button{cursor:pointer}a{color:var(--blue)}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,svg [tabindex]:focus-visible{outline:3px solid #f1a548;outline-offset:4px}[hidden]{display:none!important}header{background:#fff;border-bottom:1px solid var(--line);padding:18px 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#cbd7e8;border-radius:8px;background:#fff;color:var(--ink);font-size:16px;font-weight:650;text-decoration:none;line-height:1.35}.button:hover{background:#edf3ff}.primary{background:var(--blue);color:white;border-color:var(--blue)}.primary:hover{background:#174bc9}button:disabled{opacity:.4;cursor:default}main{max-width:1560px;margin:auto;padding:24px 32px}.lesson-nav{display:grid;grid-template-columns:repeat(6,1fr);gap:8px}.lesson-nav button{background:#fff;border:1px solid var(--line);color:var(--muted);border-radius:9px;padding:12px 10px;display:flex;gap:9px;align-items:center;justify-content:center;font-weight:650;font-size:15px;line-height:1.25}.lesson-nav button span{font:600 14px var(--mono);background:#edf1f8;border-radius:50%;width:25px;height:25px;display:grid;place-items:center;flex-shrink:0}.lesson-nav button.active{color:var(--blue);border:2px solid var(--blue);background:#f1f5ff;padding:11px 9px}.lesson-nav button.active 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310px;gap:22px;align-items:start}.visual-panel{background:white;border:1px solid var(--line);border-radius:12px;overflow:hidden;min-width:0}.visual-heading{padding:20px 24px 12px;display:flex;gap:16px;align-items:center;justify-content:space-between}.visual-heading h2{font-size:21px;margin:0;font-weight:700}.chart-badge{font-size:13px;color:#52657d;background:#f1f4fa;padding:5px 10px;border-radius:6px;white-space:nowrap}#diagram{display:block;width:100%;height:auto;min-height:285px;max-height:480px}#diagram text{font-family:var(--mono)}#diagram .sample-target{cursor:pointer}#diagram .sample-target:hover{filter:drop-shadow(0 0 5px #215bea90)}.legend{display:flex;gap:22px;flex-wrap:wrap;padding:2px 24px 15px;font-size:15px;color:var(--muted)}.legend span{display:flex;align-items:center;gap:8px}.key{width:20px;height:4px;display:inline-block;border-radius:3px}.key.source{background:#6d7d93}.key.sample{background:var(--blue);height:9px;width:9px;border-radius:50%}.key.level{background:var(--orange);height:10px;width:10px;border-radius:2px}.key.error{background:#cc3b50}.chart-actions{display:flex;align-items:center;gap:10px;flex-wrap:wrap;border-top:1px solid var(--line);padding:16px 24px}.chart-actions label{font-size:15px;display:flex;gap:7px;align-items:center}.chart-actions input{width:18px;height:18px;accent-color:var(--blue)}.chart-note{padding:0 24px 18px;margin:0;font-size:15px;color:var(--muted)}.controls{background:white;border:1px solid var(--line);border-radius:12px;padding:22px}.controls h2{font-size:21px;line-height:1.3;margin:0 0 10px}.controls p{font-size:17px;color:var(--muted);margin:0 0 18px}.controls .supporting{font-size:15px;margin:16px 0 0}.choice-buttons{display:flex;flex-direction:column;gap:9px}.choice-buttons button,.bit-buttons button{background:#f7f9fd;border:1px solid #d3ddeb;border-radius:8px;min-height:48px;font-size:19px;font-weight:700;color:var(--ink)}.choice-buttons button.active,.bit-buttons button.active{background:var(--blue);color:#fff;border-color:var(--blue)}.bit-buttons{display:grid;grid-template-columns:1fr 1fr;gap:9px}.big-fact{background:var(--light);border-radius:9px;padding:18px;margin-top:18px}.big-fact strong{font:750 40px var(--mono);display:block;color:var(--blue);line-height:1.1}.big-fact span{display:block;font-size:16px;margin-top:8px}.controls .primary{width:100%}.full-width{width:100%;margin-top:9px}.level-ladder{margin:20px 0 14px;display:flex;flex-direction:column;gap:5px}.ladder-row{display:flex;align-items:center;gap:12px;padding:7px 10px;border-radius:5px;font-size:16px;color:#63728b}.ladder-row.active{background:var(--light);color:var(--blue);font-weight:750}.ladder-row strong{margin-left:auto}.comparison-note{padding:13px;border-left:3px solid #eca04e;background:#fff6e9;font-size:16px;color:#75501d;margin-bottom:18px}.sample-inspector{display:flex;align-items:center;justify-content:space-between;gap:8px;padding:18px 22px;background:#f1f5ff;border-top:1px solid #dce6fc}.sample-inspector>div{min-width:0}.sample-inspector span{display:block;font-size:12px;color:#4c6284;font-weight:650}.sample-inspector strong{font:650 23px var(--mono);display:block;margin-top:5px;color:var(--blue);overflow-wrap:anywhere}.sample-inspector>b{font-size:22px;color:#8da3c4}.binary-cell strong{letter-spacing:3px}.code-table{display:grid;grid-template-columns:1fr 1fr;gap:7px}.code-row{font:17px var(--mono);display:flex;justify-content:space-between;padding:9px;border-radius:6px;background:#f0f3f8;border:1px solid transparent}.code-row.active{background:#fff0da;border-color:#df9b3a;color:#925113;font-weight:700}.code-row span:first-child{font-size:12px;font-family:inherit;align-self:center}.takeaway{background:#182f53;color:white;border-radius:10px;padding:19px 24px;display:flex;align-items:center;gap:25px;margin-top:22px}.takeaway>span{font-size:12px;letter-spacing:1px;font-weight:750;color:#a8c3ef;white-space:nowrap}.takeaway p{margin:0;font-size:22px;line-height:1.45}.question-row{display:flex;justify-content:space-between;gap:25px;align-items:center;border-bottom:1px solid var(--line);padding:22px 4px}.question-row p{font-size:20px;margin:5px 0 0}.question-row #answer{color:#215ea1;font-weight:650;margin-top:12px}.question-row .button{white-space:nowrap}.lesson-footer{display:flex;justify-content:space-between;align-items:center;gap:15px;padding-top:20px}.lesson-footer>span{color:#71819a;font-size:15px}.audio-status{font-size:15px;color:#3f6596;margin:12px 0 0;min-height:22px}.audio-status:empty{min-height:0;margin:0}footer{font-size:15px;color:#64748b;margin-top:28px;padding:20px 0;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:25px;flex-wrap:wrap}footer p{margin:0}footer details{max-width:900px}footer summary{cursor:pointer}footer details[open]{flex-basis:100%;max-width:none}footer details p{margin-top:14px;line-height:1.7}#size-visual{padding:25px}.formula-label{font-size:14px;letter-spacing:.6px;color:#61738f;font-weight:750;margin-bottom:12px}.equation{display:flex;flex-wrap:wrap;align-items:center;gap:12px;margin-bottom:28px}.factor{border:1px solid #d3dff3;background:#f2f6ff;padding:14px 18px;border-radius:8px;text-align:center;min-width:125px}.factor strong{display:block;font:650 29px var(--mono);color:var(--blue)}.factor span{font-size:14px;color:#50688e;display:block;margin-top:3px}.operator{font-size:26px;color:#8090aa}.size-result{padding:20px;background:#eaf5ee;border:1px solid #b9d9c4;border-radius:10px;margin:0 0 20px;font-size:22px;color:#256345}.size-result strong{font:700 32px var(--mono)}.fine-print{font-size:14px;color:#71819a;margin-bottom:0}#size-controls label{font-size:16px;font-weight:650;display:flex;justify-content:space-between;gap:8px;margin:17px 0 7px}select{width:100%;min-height:45px;padding:8px;border:1px solid #cbd7e8;background:white;border-radius:7px;color:var(--ink)}input[type=range]{width:100%;accent-color:var(--blue);cursor:pointer;margin:12px 0}#duration-label{font-size:15px;font-weight:400;color:var(--blue)}
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@media(max-width:1100px){header{padding:16px 24px}main{padding:20px 24px}.classroom-badge{display:none}.lesson-nav button{font-size:12px;gap:6px;padding:10px 7px}.lesson-nav button.active{padding:9px 6px}.lesson-nav button span{width:22px;height:22px;font-size:12px}.teaching-grid{grid-template-columns:minmax(0,1fr) 260px;gap:16px}.controls{padding:18px}.controls h2{font-size:19px}.controls p{font-size:16px}.relation-banner{padding:17px 20px;gap:17px}.relation-banner strong{font-size:30px}.relation-banner small{font-size:16px}.relation-banner p{font-size:16px;max-width:220px}.visual-heading{display:block;padding:18px 20px 8px}.chart-badge{display:inline-block;margin-top:8px;font-size:12px}.sample-inspector{padding:15px;gap:7px;flex-wrap:wrap;justify-content:flex-start}.sample-inspector strong{font-size:21px}.sample-inspector span{font-size:11px}.sample-inspector .binary-arrow{display:none}.sample-inspector .binary-cell{flex-basis:100%;border-top:1px solid #d5dff3;padding-top:10px}.chart-actions{padding:15px;gap:8px}.chart-actions .button{font-size:14px;padding:9px 11px}.legend{padding-left:20px;font-size:13px;gap:15px}.takeaway{gap:18px}.takeaway p{font-size:20px}}
@media(max-width:760px){header{padding:14px 17px}.brand{font-size:20px;gap:8px}.brand-mark{width:32px;height:32px;font-size:30px}.header-actions{gap:8px}.header-actions .button{font-size:13px;padding:8px 10px}#fullscreen{display:none}main{padding:17px}.lesson-nav{grid-template-columns:repeat(3,1fr);gap:6px}.lesson-nav button{font-size:13px;justify-content:flex-start;min-height:48px}.lesson-intro{margin:22px 0 16px}.lesson-intro h1{font-size:31px;letter-spacing:-.7px}.subtitle{font-size:18px}.teaching-grid{grid-template-columns:1fr}.controls{order:-1;padding:17px}.controls h2{font-size:20px}.controls p{margin-bottom:12px}.choice-buttons{flex-direction:row;flex-wrap:wrap;gap:7px}.choice-buttons button{flex:1;font-size:16px;min-width:90px}.bit-buttons{grid-template-columns:repeat(4,1fr)}.bit-buttons button{font-size:18px}.level-ladder{display:grid;grid-template-columns:1fr 1fr;margin:12px 0}.ladder-row{font-size:14px;gap:7px;padding:6px}.comparison-note{margin-bottom:12px;padding:10px}.controls .primary,.controls .full-width{width:auto;min-height:43px;font-size:15px}.controls .supporting{font-size:14px;margin:10px 0 0}.big-fact{margin-top:12px;padding:12px;display:flex;align-items:center;gap:15px}.big-fact strong{font-size:30px}.big-fact span{margin:0;font-size:15px}.relation-banner{flex-wrap:wrap;gap:10px 15px;padding:16px}.relation-banner strong{font-size:27px}.relation-banner small{font-size:15px}.relation-name{font-size:10px}.relation-arrow{font-size:25px}.relation-banner p{flex-basis:100%;max-width:none;margin:3px 0 0;font-size:16px}.visual-heading{padding:16px 16px 8px}.visual-heading h2{font-size:20px}#diagram{min-height:230px}.legend{padding:0 16px 13px;font-size:12px;gap:13px}.sample-inspector strong{font-size:19px}.sample-inspector span{font-size:10px}.sample-inspector .binary-cell{flex-basis:auto;border:0;padding:0}.sample-inspector{gap:12px}.sample-inspector>b{font-size:18px}.chart-actions .button{font-size:13px}.chart-note{font-size:14px;padding:0 16px 16px}.takeaway{display:block;padding:18px}.takeaway p{font-size:20px;margin-top:7px}.question-row{align-items:flex-start;gap:15px}.question-row p{font-size:18px}.question-row .button{font-size:13px;white-space:normal;min-width:95px;padding:10px}.lesson-footer .button,.lesson-footer .primary{font-size:14px;padding:10px 13px}.lesson-footer>span{font-size:12px}.code-table{grid-template-columns:repeat(4,1fr)}.code-row{font-size:14px;padding:7px;gap:5px}.code-row span:first-child{font-size:10px}.factor{min-width:90px;padding:12px}.factor strong{font-size:24px}.factor span{font-size:12px}.equation{gap:8px}#size-visual{padding:18px}.size-result{font-size:19px}.size-result strong{font-size:25px}footer{font-size:14px;gap:15px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}

.real-depths{font-family:var(--mono);font-size:14px!important;color:#395e99!important;line-height:1.8}
@media(max-width:500px){#diagram-area{overflow-x:auto}#diagram{min-width:560px;max-height:none}.relation-banner strong{font-size:24px}.relation-banner small{font-size:13px}.relation-name{font-size:9px}.relation-banner{gap:10px}.code-table{grid-template-columns:1fr 1fr}.controls .primary,.controls .full-width{width:100%}.visual-panel .chart-note:after{content:' On a small screen, swipe the diagram sideways.'}}