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@media(min-width:1600px){main{padding:40px 50px}.drawing-stage svg{max-height:480px}.step-body{padding:22px 28px}.explain-block p{font-size:13px}.topbar{padding:0 50px}}
@media(max-width:1150px){.sidebar{width:218px;padding:24px 15px}.shell{margin-left:218px}main{padding:25px 22px}.topbar{padding:0 22px}.workspace{grid-template-columns:minmax(0,1.1fr) minmax(290px,1fr)}.page-heading h1{font-size:26px}.step-body{padding:16px}.source-line{display:block}.source-line span{display:block;margin-top:6px}.drawing-stage svg{min-height:230px}.metric{padding:8px 10px}.panel-head{padding:13px}.reflection{grid-template-columns:1fr 220px}.task-grid{grid-template-columns:1fr 1fr}}
@media(max-width:900px){.workspace{grid-template-columns:1fr}.drawing-stage svg{max-height:420px}.steps-panel .step-body{padding:20px 24px}.step-body h3{font-size:19px}.below-grid,.reflection{grid-template-columns:1fr}.self-rating{border-left:0;border-top:1px solid var(--line);padding:10px 0 0}.self-rating button{display:inline-block;width:auto;margin-right:8px}.update-grid,.glossary-grid{grid-template-columns:1fr}.mini-progress{display:none}.brand{font-size:18px}.brand small{font-size:8px}.top-actions>span{display:none}}
@media(max-width:650px){.sidebar{position:relative;width:100%;padding:18px 16px 14px}.brand{font-size:21px}.brand svg{width:32px;height:32px}.side-caption,.side-footer{display:none}.main-nav{display:flex;gap:4px;margin-top:16px;overflow:auto}.main-nav button{font-size:11px;white-space:nowrap;padding:8px 10px}.main-nav button span{width:20px;font-size:13px}.side-section{margin-top:14px;padding-top:12px}.side-section>.eyebrow{display:none}.search{margin:0 0 8px}.side-section select{display:none}.question-list{display:flex;gap:6px;overflow:auto;margin-top:3px;padding:0 0 3px;max-height:70px}.question-nav{width:auto;min-width:55px;padding:8px 11px;justify-content:center}.question-nav .nav-title{display:none}.question-nav .num{min-width:0}.shell{margin-left:0}.topbar{height:45px;padding:0 17px;font-size:10px}.topbar .text-button{font-size:10px;padding-left:10px}main{padding:24px 15px 10px}.page-heading{margin-bottom:20px}.page-heading h1{font-size:24px;letter-spacing:-.8px}.page-heading .eyebrow{font-size:8px;letter-spacing:1.1px}.page-heading p{font-size:11px}.question-card{padding:18px}.question-heading{align-items:flex-start;gap:8px}.question-heading h2{font-size:17px}.icon-button{font-size:10px;padding:5px 8px}.source-tag{display:block;margin:6px 0 0;font-size:9px}.stem{font-size:12px}.workspace{gap:15px}.panel-head{padding:13px 14px}.panel-head select{max-width:180px}.drawing-stage svg{min-height:230px}.model-controls{padding:12px}.play-row{gap:6px}.play-row label{display:none}.play-row output{min-width:45px}.toggle-row{gap:12px}.inspect{min-height:110px}.below-grid{gap:15px}.card{padding:20px}.reflection{gap:10px}.task-grid{grid-template-columns:1fr}.stat-grid{gap:9px}.stat-card{padding:15px 11px}.stat-card strong{font-size:28px}.stat-card span{font-size:9px}.daily-toolbar{gap:10px}.daily-toolbar label{font-size:10px}.section-title{margin-top:24px}.section-title h2{font-size:16px}.page-footer{padding:20px 17px;font-size:8px;display:block}.page-footer span{display:block;margin-top:5px}#toast{left:50%;max-width:90%;width:max-content}.audit-table th,.audit-table td{padding:8px 5px;font-size:10px}}
.stem{font-size:14px}.explain-block p{font-size:14px}.principle-box p{font-size:13px}.check-line p{font-size:12px}.result-card>p,.quiz-card>p{font-size:13px}.quiz-option{font-size:12px}.primary-button,.secondary-button{min-height:37px}.inspect p{font-size:12px}.source-line{font-size:11px}.source-tag{font-size:11px}
@media(max-width:650px){.explain-block p{font-size:13px}.principle-box p{font-size:12px}.step-tabs button{width:32px;height:32px}.primary-button,.secondary-button{min-height:40px}.stem{font-size:13px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}
/* v1.1: give the mechanism its own full-width drawing desk. */
[hidden]{display:none!important}
#learn-view>.page-heading{display:none}
.sidebar{width:206px;padding:25px 16px}.shell{margin-left:206px}
.brand{font-size:20px}.brand small{font-size:8px}.brand svg{width:35px}
.side-caption{font-size:11px;margin:22px 0}.main-nav{margin-top:25px}.main-nav button{padding:13px 12px;font-size:13px}
main{max-width:1500px;padding:22px 28px}.topbar{height:48px;padding:0 28px}
.question-card{padding:19px 24px;margin-bottom:18px}.question-heading h2{font-size:21px;margin:10px 0 6px}.stem{margin:10px 0;line-height:1.8}
.source-line{display:flex;align-items:baseline;gap:22px}.source-details{font-size:11px;color:var(--muted);flex:1}.source-details summary{cursor:pointer;width:max-content}.source-details span{display:block;margin-top:8px}
.workspace{display:grid;grid-template-columns:minmax(0,1fr);gap:18px}
.canvas-panel{min-width:0}.panel-head{padding:14px 22px}.panel-head h3{font-size:15px}.panel-head select{max-width:320px}
.diagram-toolbar{display:flex;flex-wrap:wrap;align-items:center;gap:12px;padding:13px 22px 0}.mode-switch{display:flex;border:1px solid var(--line);border-radius:8px;padding:3px;background:#f2f5ee}.mode-switch button{border:0;background:none;border-radius:5px;padding:7px 15px;font-size:12px}.mode-switch button[aria-pressed=true]{background:var(--deep);color:#fffefa}.diagram-toolbar>select{border:1px solid var(--line);background:var(--white);padding:6px;border-radius:5px;max-width:240px}.diagram-toolbar .text-button{font-size:11px;padding:6px 0}.diagram-toolbar #expand-diagram{margin-left:auto}
.diagram-hint{font-size:11px;color:var(--muted);margin:8px 22px 12px;line-height:1.7}
.drawing-stage{padding:0;min-height:0;background:#f8faf6}.drawing-stage svg{display:block;width:100%;height:clamp(400px,56vh,640px);min-height:0;max-height:none;background:none}.canvas-panel.expanded .drawing-stage svg{height:78vh;min-height:500px}.drawing-stage #model-status{position:static;min-height:24px;padding:2px 22px 5px;font-size:10px;color:#7b7569}
.model-controls{padding:14px 22px}.play-row{gap:12px}.play-row input[type=range]{flex:1}.toggle-row{margin-top:10px}.keyframes{margin-top:10px}.keyframes button{font-size:11px}.construction-controls{display:flex;align-items:center;flex-wrap:wrap;gap:12px;margin-top:14px;padding-top:14px;border-top:1px solid var(--line);font-size:12px}.construction-controls input{flex:1;min-width:100px;accent-color:var(--teal)}.construction-controls output{min-width:40px}
.metrics{grid-template-columns:repeat(3,minmax(0,1fr))}.metric strong{font-size:19px}.inspect{padding:15px 22px;min-height:85px}.inspect p{margin:4px 0 0;line-height:1.8}
.step-tabs{padding:15px 22px 0;flex-wrap:wrap}.step-body{display:grid;grid-template-columns:1fr 1fr;gap:18px 28px;padding:18px 24px}.step-kicker,.step-body>h3{grid-column:1/-1;margin:0}.step-body>h3{font-size:22px}.explain-block{margin:0;padding:0;border:0}.explain-block p{font-size:14px;line-height:1.9;margin:8px 0}.principle-box{margin:0;padding:15px 18px}.check-line{margin:0;padding:15px 0}.step-footer{padding:16px 24px}.steps-panel>.concept-links{margin:0 24px 16px;padding-top:12px}
.below-grid{grid-template-columns:minmax(0,1fr)}.quiz-card{padding:25px}.quiz-card>h3{font-size:21px}.quiz-card #quiz-prompt{font-size:15px;line-height:1.9;max-width:920px}.quiz-card #quiz-principle{font-size:11px;color:var(--teal)}
#quiz-options{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:18px 0}.quiz-option{margin:0;font-size:13px;line-height:1.8;padding:14px;align-items:flex-start}.quiz-option input{margin-top:5px;flex-shrink:0}.feedback{font-size:13px;line-height:1.9}.option-reason{padding:14px 18px;border-left:3px solid #cbd2c6;background:#f5f6f0;margin-top:10px;font-size:12px;line-height:1.8}.option-reason.correct{border-color:var(--teal);background:#edf4e8}.option-reason p{margin:5px 0 0}
.principle-search{max-width:500px;margin:0 0 20px;background:var(--white);border-color:var(--line);color:var(--ink)}.principle-search input{color:var(--ink)}.principle-search input::placeholder{color:var(--muted)}.principle-count{display:block;color:var(--muted);margin-top:12px}.principle-detail{margin-top:18px;padding:30px}.principle-detail h1{font-size:27px;line-height:1.5}.principle-summary{color:var(--teal);font-size:15px}.principle-sections{display:grid;grid-template-columns:1fr 1fr;gap:22px 32px;margin:25px 0}.principle-sections section{border-top:1px solid var(--line);padding-top:18px}.principle-sections p{white-space:pre-line;font-size:14px;line-height:2}.principle-examples{padding-top:22px;border-top:1px solid var(--line)}.principle-examples h2{font-size:20px}.principle-examples .term-links button{font-size:12px;padding:9px 12px}
.diagram-step-nav{display:flex;align-items:center;gap:10px;padding:10px 22px;background:#eff4e9;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.diagram-step-nav select{min-width:0;flex:1;border:0;background:transparent;color:var(--ink);font-size:12px}.diagram-step-nav button{border:1px solid #cad7c5;background:#fffefa;border-radius:6px;padding:5px 11px;font-size:12px}
@media(max-width:1150px){main{padding:18px}.topbar{padding:0 18px}.sidebar{width:190px;padding:22px 13px}.shell{margin-left:190px}.brand{font-size:18px}.brand svg{width:30px}.main-nav button{font-size:12px}.question-card{padding:17px 20px}.question-heading h2{font-size:19px}.diagram-toolbar{gap:10px;padding:12px 18px 0}.diagram-hint{margin-left:18px;margin-right:18px}.drawing-stage svg{height:460px}.step-body{padding:20px;gap:18px}.reflection{grid-template-columns:1fr 230px}}
@media(max-width:760px){.sidebar{position:relative;width:100%;padding:16px}.shell{margin-left:0}.brand{font-size:21px}.side-caption,.side-footer{display:none}.main-nav{display:flex;margin-top:12px;gap:4px;overflow:auto}.main-nav button{padding:8px 10px;white-space:nowrap;font-size:11px}.main-nav button span{font-size:13px;width:18px}.side-section{margin-top:12px;padding-top:10px}.side-section>.eyebrow,.side-section>select{display:none}.side-section .search{margin:0 0 8px}.question-list{display:flex;overflow:auto;gap:5px;max-height:48px;padding:0}.question-nav{width:auto;min-width:44px;justify-content:center;padding:6px 9px}.question-nav .nav-title{display:none}.question-nav .num{min-width:0}main{padding:16px 12px}.question-card{padding:16px}.question-heading h2{font-size:18px}.source-line{display:block}.source-details{margin-top:5px}.panel-head{padding:12px 15px}.diagram-toolbar{padding:10px 14px 0;gap:10px}.mode-switch button{padding:6px 10px;font-size:11px}.diagram-toolbar #expand-diagram{margin-left:0}.diagram-hint{margin:8px 15px 10px}.drawing-stage svg{height:360px}.canvas-panel.expanded .drawing-stage svg{height:65vh;min-height:400px}.model-controls{padding:12px 15px}.step-body{grid-template-columns:1fr;padding:18px}.step-kicker,.step-body>h3{grid-column:auto}.step-body>h3{font-size:20px}.steps-panel>.concept-links{margin:0 18px 14px}.step-footer{padding:14px 18px}#quiz-options{grid-template-columns:1fr}.quiz-card{padding:20px}.quiz-option{font-size:13px}.reflection{grid-template-columns:1fr}.self-rating{border-left:0;border-top:1px solid var(--line);padding:10px 0}.self-rating button{display:inline-block;width:auto}.principle-sections{grid-template-columns:1fr}.principle-detail{padding:21px}.principle-detail h1{font-size:23px}.diagram-step-nav{padding:9px 14px;gap:6px}.diagram-step-nav button{padding:5px 8px}#toast{left:50%}.metrics{grid-template-columns:repeat(3,minmax(0,1fr))}.metric{padding:10px}.metric strong{font-size:17px}}
.drawing-stage{display:block;flex:none}.drawing-stage svg{flex:none}.side-caption{margin:14px 0 0}.main-nav{margin-top:18px}.main-nav button{padding:9px 10px}.main-nav button span{font-size:18px}.side-section{margin-top:18px;padding-top:16px}.side-footer{padding-top:12px}.question-nav{font-size:11px;padding:10px 9px}@media(max-width:760px){.main-nav{margin-top:12px}.main-nav button{padding:8px 10px}.main-nav button span{font-size:13px}.side-section{margin-top:12px;padding-top:10px}.question-nav{padding:6px 9px}}

.canvas-panel>.construction-controls{margin:0;padding:12px 22px;background:#f4f7ef;border-top:0;border-bottom:1px solid var(--line)}

/* v1.2: the operation and its fixed reference stay beside the drawing controls. */
.step-visual-guide{padding:12px 22px;background:#f6f8f1;border-bottom:1px solid var(--line);display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px 18px}.guide-item{font-size:11px;line-height:1.7;min-width:0}.guide-item strong{display:block;margin-bottom:4px}.guide-item span{color:#576d64}.guide-fixed strong{color:#697e87}.guide-moving strong{color:#bd7130}.guide-added strong{color:#247c69}.guide-why{grid-column:1/-1;margin:0;padding-top:8px;border-top:1px dashed #dbe2d3;font-size:11px;line-height:1.8;color:#365b4d}.construction-controls .text-button{font-size:11px}.drawing-stage #model-status{min-height:35px;font-size:11px}.drawing-stage svg{background:#f8faf6}@media(max-width:760px){.step-visual-guide{grid-template-columns:1fr;padding:12px 15px;gap:7px}.guide-item strong{display:inline;margin-right:10px}.guide-why{grid-column:auto}.canvas-panel>.construction-controls{padding:10px 15px;gap:8px}.construction-controls input{min-width:90px}.construction-controls .secondary-button{padding:6px 9px;font-size:11px}}
.canvas-panel.expanded{position:fixed;inset:12px;z-index:40;overflow:auto;box-shadow:0 0 0 100vmax #142e2988}.canvas-panel.expanded .drawing-stage svg{height:auto;min-height:0;aspect-ratio:8/5}.canvas-panel.expanded .panel-head{position:sticky;top:0;background:var(--white);z-index:2}.canvas-panel.expanded .diagram-toolbar{position:sticky;top:53px;background:var(--white);z-index:2;padding-bottom:12px}@media(max-width:760px){.canvas-panel.expanded{inset:6px}.canvas-panel.expanded .diagram-toolbar{top:50px}}
.drawing-stage [data-info]:hover,.drawing-stage [data-info]:focus{filter:none;outline:none}.drawing-stage .is-focused{filter:none}