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@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}

/* KaTeX typography for all lesson equations */
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.tex-inline .katex{font-size:1.05em}
@media(max-width:600px){.tex-display.formula{padding:17px 9px;font-size:18px}}

/* v0.3: equation-by-equation derivations */
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.derivation-reason{color:#546b63;font-size:14px;line-height:1.8;margin:0 0 6px}
@media(max-width:600px){.derivation-line .derivation-math{font-size:18px}.derivation-stage{padding:16px}}

/* Definition research lab: responsive sliders, live motion and quantitative comparisons */
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.definition-controls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px 22px;padding:16px 0}
.definition-controls label{display:grid;gap:9px;font-size:13px;font-weight:650}
.definition-controls output{float:right;color:var(--teal);font-variant-numeric:tabular-nums;font-weight:800}
.definition-controls input,.definition-player input{accent-color:var(--teal);width:100%;min-width:0}
.definition-track-frame{background:#f3f8f4;border:1px solid var(--line);border-radius:14px;padding:12px 12px 15px}
#def-track{display:block;width:100%;height:auto;max-height:220px}
.definition-player{display:flex;align-items:center;flex-wrap:wrap;gap:10px;padding:8px 8px 0}
.definition-player label{font-size:13px;white-space:nowrap}
.definition-player input{flex:1 1 140px}
.definition-stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px;margin:16px 0}
.definition-stats>div{background:#eef5f1;border:1px solid #d9e8df;border-radius:12px;padding:14px 10px}
.definition-stats small{display:block;color:#55756a;font-size:11px;line-height:1.5}
.definition-stats strong{display:block;font-size:clamp(15px,1.8vw,21px);color:var(--green);margin-top:8px;font-variant-numeric:tabular-nums}
.definition-math-area{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.definition-math-area>div{min-width:0}
.definition-math-area .formula{font-size:clamp(14px,1.6vw,21px);padding:16px 8px}
.definition-lab [data-def-question]{font-size:12px}
#def-question-response{font-size:14px;line-height:1.8}
@media(max-width:900px){.definition-stats{grid-template-columns:repeat(2,minmax(0,1fr))}.definition-math-area{grid-template-columns:1fr}}
@media(max-width:550px){.definition-controls{grid-template-columns:1fr}.definition-player{gap:7px}.definition-stats strong{font-size:17px}}

/* Acceleration concept lab v0.5 */
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.acc-controls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px;padding:20px 0}
.acc-controls label{display:grid;gap:10px;font-size:13px;font-weight:700}
.acc-controls output{font-size:12px;color:var(--teal);font-variant-numeric:tabular-nums}
.acc-controls input,.acc-player input{width:100%;accent-color:var(--teal);min-width:0}
.acc-figure{border-radius:16px;border:1px solid var(--line);overflow:hidden;background:#f4f9f6}
.acc-figure svg{display:block;width:100%;height:auto;max-height:320px}
.acc-player{display:flex;gap:10px;align-items:center;flex-wrap:wrap;padding:10px}
.acc-player label{white-space:nowrap;font-size:12px}
.acc-player input{flex:1 1 130px}
.acc-results{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;margin:14px 0}
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.acc-results strong{display:block;font-size:clamp(15px,2vw,22px);margin-top:8px;color:var(--green);font-variant-numeric:tabular-nums}
@media(max-width:600px){.acc-controls{grid-template-columns:1fr}.acc-results{grid-template-columns:1fr}.acc-player{gap:7px}}

/* Structured mechanics curriculum and three-perspective learning */
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.mechanics-chapter-list{display:grid;gap:6px;position:sticky;top:18px;max-height:80vh;overflow:auto}
.mechanics-chapter-button{display:flex;align-items:center;gap:10px;padding:11px;text-align:left;border:1px solid var(--line);background:white;border-radius:12px;color:var(--ink)}
.mechanics-chapter-button.active{background:var(--light);border-color:#a8ccba;color:var(--green)}
.mechanics-chapter-button.is-done .mechanics-index{background:#d9efe4;color:#19644f}
.mechanics-chapter-button strong{font-size:12px;display:block;line-height:1.5}
.mechanics-chapter-button small{display:block;color:var(--muted);font-size:10px}
.mechanics-index{font-weight:800;font-size:13px;color:var(--teal)}
.mechanics-topic h3{margin:25px 0 9px}
.mechanics-topic>p{font-size:14px;color:#536e63}
.mechanics-equation-step{border-top:1px solid var(--line);padding:14px 0 4px}
.mechanics-equation-step strong{font-size:13px}
.mechanics-equation-step p{font-size:13px;color:var(--muted)}
.mechanics-equation-step .formula{font-size:clamp(17px,2vw,25px);overflow-x:auto}
.mechanics-parameter-grid{display:grid;grid-template-columns:1fr;gap:8px;padding:14px 2px}
.mechanics-parameter-grid label{font-weight:700;font-size:12px}
.mechanics-parameter-grid input{width:100%;accent-color:var(--teal)}
.mechanics-output{background:var(--light);padding:14px;border-radius:12px}
.mechanics-output strong{color:var(--green);font-size:17px}
.mechanics-output p{font-size:13px;color:#4b675b;margin:6px 0 0}
.mechanics-perspectives{display:grid;gap:8px}
.mechanics-perspectives section{border:1px solid var(--line);padding:12px;border-radius:11px;background:#f9fbf8}
.mechanics-perspectives h3{margin:0 0 8px;font-size:14px}
.mechanics-perspectives p{font-size:13px;line-height:1.8;margin:0}
@media(max-width:850px){.mechanics-layout{grid-template-columns:1fr}.mechanics-chapter-list{position:static;grid-template-columns:repeat(2,minmax(0,1fr));max-height:none}}
@media(max-width:520px){.mechanics-chapter-list{grid-template-columns:1fr}.mechanics-topic{padding:17px}}

/* Newton's force analysis lab */
.force-lab-page>section{margin-top:21px}
.force-control-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin:18px 0}
.force-control-grid label{display:grid;gap:8px;font-weight:700;font-size:13px}
.force-control-grid label:first-child{grid-column:1/-1}
.force-control-grid input{width:100%;accent-color:var(--teal)}
.force-control-grid select{max-width:320px;background:white;border:1px solid var(--line);padding:8px;border-radius:9px}
.force-control-grid output{font-variant-numeric:tabular-nums;color:var(--teal)}
.force-scene{background:#f4f9f6;border:1px solid var(--line);border-radius:14px;overflow:hidden}
.force-scene svg{display:block;width:100%;height:auto;max-height:300px}
.force-play{display:flex;gap:12px;align-items:center;flex-wrap:wrap;margin:14px 0}
.force-play input{flex:1 1 130px;accent-color:var(--teal)}
.force-play label{font-size:12px;white-space:nowrap}
.force-metrics{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:9px;margin:15px 0}
.force-metrics>div{background:var(--light);padding:12px;border-radius:11px}
.force-metrics small{display:block;color:#5c766d;font-size:11px}
.force-metrics strong{display:block;font-size:clamp(14px,1.8vw,19px);margin-top:6px;font-variant-numeric:tabular-nums}
.force-fbd-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.force-fbd{background:#f6faf7;border:1px solid var(--line);border-radius:12px;padding:12px;min-width:0}
.force-fbd svg{width:100%;height:auto}
.force-fbd h3{font-size:15px}
.force-fbd>div{color:#536b61;font-size:12px}
.force-thinking{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;margin:15px 0}
.force-thinking>div{background:#f5f9f5;border-radius:12px;padding:14px;border:1px solid var(--line)}
.force-thinking h3{font-size:14px}
.force-thinking p{font-size:13px;line-height:1.8}
@media(max-width:900px){.force-metrics{grid-template-columns:repeat(2,minmax(0,1fr))}.force-thinking{grid-template-columns:1fr}}
@media(max-width:600px){.force-control-grid,.force-fbd-grid{grid-template-columns:1fr}}

/* Conservation: explicitly compare conserved versus dissipated physical quantities */
.conservation-page>section{margin-top:18px}
.cons-controls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:17px;margin:18px 0}
.cons-controls label{display:grid;gap:8px;font-size:13px;font-weight:700}
.cons-controls input{width:100%;accent-color:var(--teal)}
.cons-controls output{font-variant-numeric:tabular-nums;color:var(--teal)}
.cons-bars{display:grid;gap:13px;margin:18px 0}
.cons-bars>div{font-size:13px;font-weight:600}
.cons-bars strong{font-size:13px;color:var(--green)}
.cons-bar-track{height:18px;background:#e6eee9;border-radius:8px;overflow:hidden;margin:5px 0}
.cons-bar-track>span{display:block;height:100%;background:#428b7d;width:0;transition:width .18s;border-radius:8px}
#cons-diss-bar{background:#c08349}
@media(max-width:600px){.cons-controls{grid-template-columns:1fr}}

/* v0.9 advanced mechanics laboratories */
.advanced-controls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;margin:18px 0}
.advanced-controls label{display:grid;gap:6px;font-size:13px;font-weight:650}
.advanced-controls input,#adv-seek{width:100%;accent-color:var(--teal)}
.advanced-controls output{color:var(--teal);font-variant-numeric:tabular-nums}
.advanced-step{border-top:1px solid var(--line);padding:14px 0 5px}
.advanced-step strong{font-size:14px}
#advanced-plot{display:block;width:100%;height:auto;border:1px solid var(--line);border-radius:13px}
#adv-result{font-variant-numeric:tabular-nums;overflow-wrap:anywhere}
@media(max-width:600px){.advanced-controls{grid-template-columns:1fr}}

/* Japanese-English course switch, preserving existing responsive layout */
.language-picker{display:flex;align-items:center;gap:8px;font-size:11px;font-weight:700;color:var(--green)}
.language-picker select{border:1px solid #b3c8ba;background:#fff;color:var(--green);border-radius:10px;padding:8px 10px;font-size:13px;font-weight:700;max-width:120px}
.i18n-notice{background:#fff7e8;border:1px solid #e1cba0;border-radius:12px;padding:14px 18px;margin:14px auto 0;max-width:1040px;color:#655230;font-size:13px;line-height:1.75}
@media(max-width:760px){.language-picker span{display:none}.language-picker select{max-width:100px;font-size:12px}.topbar-right{gap:8px}.topbar .edition{display:none}}