.physics-page{--muted:#5f746c;background:#f6f8f5}
.physics-shell{max-width:1440px;padding:26px 4% 0}
.physics-breadcrumb{display:flex;gap:12px;align-items:center;font-size:12px;color:var(--muted);margin-bottom:24px}.physics-breadcrumb a{text-decoration:none}
.physics-hero{display:flex;justify-content:space-between;align-items:center;gap:24px;margin-bottom:28px}
.physics-hero h1{font-size:clamp(27px,3.2vw,42px);letter-spacing:-.7px;margin:10px 0}.physics-hero p{color:var(--muted);margin:0;font-size:15px}
.physics-text-link{font-weight:600;text-decoration:none;display:inline-flex;align-items:center;gap:12px;min-height:44px;font-size:14px}.physics-text-link:hover{text-decoration:underline}.physics-hero>.physics-text-link{flex-shrink:0}
.experiment-tabs{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin-bottom:22px}
.experiment-tabs button{display:flex;align-items:center;gap:12px;padding:16px;text-align:left;border:1px solid #dce5dd;background:white;border-radius:14px;min-width:0;transition:background .15s,border-color .15s}
.experiment-tabs button:hover{background:#eef5ef;border-color:#a3c1ad}.experiment-tabs button[aria-selected=true]{background:#e8f2eb;border-color:#338569;box-shadow:inset 0 0 0 1px #338569}
.experiment-symbol{width:40px;height:40px;flex:0 0 40px;display:grid;place-items:center;border-radius:11px;background:#f0f4ef;color:#537264;font:26px "Segoe UI",sans-serif}[aria-selected=true] .experiment-symbol{background:var(--green);color:white}
.experiment-tabs strong{display:block;font-size:16px}.experiment-tabs small{display:block;font-size:11px;color:var(--muted);margin-top:4px}.experiment-number{margin-left:auto;align-self:start;color:#74887d;font-size:11px}
.physics-workbench{display:grid;grid-template-columns:300px minmax(0,1fr);align-items:start;gap:22px}
.physics-card{border:1px solid #dce5dd;border-radius:18px;background:#fff;min-width:0;overflow-wrap:anywhere}.physics-controls{padding:22px}
.physics-card-heading{display:flex;align-items:center;justify-content:space-between;gap:12px}.physics-card-heading h2{font-size:19px}.step-badge{font-size:10px;color:#62796c;background:#f0f5ee;padding:5px 9px;border-radius:20px;white-space:nowrap}
.panel-hint{font-size:12px;color:var(--muted);margin:7px 0 22px}.physics-inputs{display:grid;gap:19px}.physics-field{min-width:0}.physics-field-heading{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:3px}
.physics-field label{font-size:13px;font-weight:600;line-height:1.6}.physics-field label small{display:block;font-size:11px;color:var(--muted);font-weight:400}
.physics-field input[type=number]{width:86px;min-width:0;min-height:44px;border:1px solid #cddcd1;border-radius:8px;padding:8px;text-align:center;color:var(--green);font:600 16px "Segoe UI",sans-serif;background:#f8fbf8}
.physics-field input[type=range]{width:100%;accent-color:var(--green);min-height:32px;margin:0;cursor:pointer}.physics-field select{width:100%;margin-top:8px;min-height:44px;font-size:13px}
.range-ends{display:flex;justify-content:space-between;color:var(--muted);font:11px "Segoe UI",sans-serif}.physics-field input[aria-invalid=true]{border:2px solid #b23a32;background:#fff3ef}
.physics-error{font-size:13px;line-height:1.7;color:#9a3225;background:#fff2eb;padding:10px;border-radius:8px}.physics-error:empty{display:none}
.physics-presets{border-top:1px solid var(--line);padding-top:17px;margin-top:20px}.physics-presets>span{display:block;font-size:11px;color:var(--muted);margin-bottom:9px}.physics-presets>div{display:flex;flex-wrap:wrap;gap:7px}
.physics-presets button{background:white;border:1px solid #d3dfd5;border-radius:8px;padding:8px 10px;font-size:12px;min-height:44px}.physics-presets button:hover{background:#e8f2eb;border-color:#338569}
.physics-tip{display:flex;align-items:start;gap:10px;background:#f6f5e9;color:#6c6334;border-radius:10px;padding:13px;margin-top:18px}.physics-tip>span{font-size:21px}.physics-tip p{font-size:12px;line-height:1.9;margin:0}
.physics-stage{overflow:hidden}.physics-stage>.physics-card-heading{padding:22px 24px 14px}.scene-eyebrow{display:block;font-size:10px;color:var(--muted);letter-spacing:.6px;margin-bottom:5px}
.dimension-badge{border:1px solid #c9ddd1;background:#eff7f1;color:#226d51;border-radius:6px;font:600 11px "Segoe UI",sans-serif;padding:7px 10px;white-space:nowrap}
.scene-toolbar{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:0 24px 14px;flex-wrap:wrap}.scene-legend{display:flex;gap:16px;font-size:11px;color:#50695d;flex-wrap:wrap}
.scene-legend span{display:inline-flex;gap:6px;align-items:center}.scene-legend i{height:7px;width:7px;border-radius:50%;background:var(--legend-color)}.vector-toggle{font-size:11px;display:flex;align-items:center;gap:5px;min-height:32px;cursor:pointer}.vector-toggle input{accent-color:var(--green);width:16px;height:16px}
.physics-figure{margin:0 14px}.physics-figure svg{display:block;width:100%;height:auto;border-radius:12px;background:#f1f7f2;border:1px solid #e0eae1}
.physics-figure svg text{font-family:"Segoe UI","Nirmala UI",sans-serif;font-size:14px;fill:#405e50}.physics-figure svg .svg-small{font-size:12px}.physics-figure svg .svg-large{font-size:18px;font-weight:600}
.physics-figure figcaption{font-size:12px;color:var(--muted);padding:12px 10px;line-height:1.8;min-height:48px}
.physics-player{padding:16px 24px 17px;background:#fbfcfa;border-top:1px solid var(--line)}.playback-actions{display:flex;align-items:center;gap:8px;flex-wrap:wrap}.physics-player button{min-height:44px;font-size:13px;padding:10px 17px;border-radius:9px}.physics-player #launch{min-width:112px}
.playback-speed{margin-left:auto;display:flex;align-items:center;gap:8px;font-size:12px;color:var(--muted)}.playback-speed select{min-height:44px;font-size:13px;padding:7px}
.physics-timeline{display:flex;align-items:center;gap:12px;margin-top:13px;font-size:12px}.physics-timeline input{flex:1;min-width:0;min-height:32px;accent-color:var(--green);cursor:pointer}.physics-timeline output{font:12px "Segoe UI","Nirmala UI",sans-serif;min-width:95px;text-align:right}#timelineHint{margin:0;color:var(--muted);font-size:11px}
.physics-stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px;margin:22px 0}.physics-stats>div{padding:19px 21px;background:white;border:1px solid #dce5dd;border-radius:13px;min-width:0}.physics-stats dt{font-size:12px;color:var(--muted);margin-bottom:8px}.physics-stats dd{font:650 26px "Segoe UI","Nirmala UI",sans-serif;margin:0;color:#245c45;overflow-wrap:anywhere}.physics-stats dd small{font-size:12px;font-weight:400;margin-left:4px;color:var(--muted)}
.physics-learning{display:grid;grid-template-columns:1fr 1fr;gap:22px}.concept-card,.physics-calculation{padding:24px}.concept-card h2{font-size:21px;line-height:1.7}.concept-card>p{font-size:14px;line-height:1.95;color:#4e685c}.physics-formula{font:600 18px "Segoe UI",sans-serif;background:#edf5ee;border-radius:9px;padding:16px;color:var(--green);line-height:1.8}.concept-card .physics-assumption{font-size:12px;color:#6c7158}
.physics-calculation summary{cursor:pointer;font-size:17px;font-weight:600;min-height:44px;line-height:1.8}.physics-calculation ol{padding-left:24px;margin:9px 0 0}.physics-calculation li{padding:0 0 12px 6px;line-height:1.9;font-size:13px;color:#4e685c}.physics-calculation li::marker{color:var(--green);font-weight:700}
.physics-page footer{font-size:12px;gap:14px;flex-wrap:wrap}.physics-page footer a{text-decoration:none;min-height:44px;display:inline-flex;align-items:center}.sr-only{position:absolute;width:1px;height:1px;padding:0;overflow:hidden;clip-path:inset(50%);white-space:nowrap}
#experimentPanel:focus-visible,summary:focus-visible{outline:3px solid #dcaa3a;outline-offset:4px}
.child-mode.physics-page .panel-hint,.child-mode.physics-page .physics-tip p,.child-mode.physics-page .physics-figure figcaption{font-size:13px}.child-mode.physics-page .concept-card>p,.child-mode.physics-page .physics-calculation li{font-size:15px}
@media(min-width:1500px){.physics-shell{padding-left:40px;padding-right:40px}}
@media(max-width:1100px){.physics-workbench{grid-template-columns:270px minmax(0,1fr);gap:16px}.physics-controls{padding:18px}.experiment-tabs button{padding:12px;gap:9px}.experiment-number{display:none}.physics-stats>div{padding:16px}.physics-stats dd{font-size:23px}}
@media(max-width:850px){.physics-workbench{grid-template-columns:minmax(0,1fr)}.physics-controls{order:2}.physics-inputs{grid-template-columns:1fr 1fr;gap:18px 28px}.physics-presets{margin-top:16px}.physics-tip{margin-top:14px}.physics-hero{align-items:start}.physics-hero>.physics-text-link{display:none}.experiment-tabs{gap:8px}.experiment-symbol{width:30px;height:34px;flex-basis:30px;font-size:23px}.experiment-tabs strong{font-size:14px}.experiment-tabs small{font-size:10px}.physics-learning{gap:16px}.physics-stats{gap:10px}}
@media(max-width:600px){.physics-shell{padding:20px 16px 0}.physics-breadcrumb{margin-bottom:18px}.physics-hero{margin-bottom:22px}.physics-hero h1{font-size:29px;line-height:1.6;letter-spacing:-.4px}.physics-hero h1 em{display:block}.physics-hero p{font-size:13px;line-height:1.95}.experiment-tabs{grid-template-columns:1fr 1fr;gap:8px;margin-bottom:16px}.experiment-tabs button{padding:12px;min-height:72px}.experiment-tabs small{font-size:10px}.physics-stage>.physics-card-heading{padding:18px 16px 12px}.scene-toolbar{padding:0 16px 10px;gap:6px}.scene-legend{gap:10px;font-size:10px}.physics-figure{margin:0 8px}.physics-figure svg{aspect-ratio:1.2;object-fit:contain}.physics-figure figcaption{padding:10px 8px}.physics-player{padding:14px 16px}.physics-timeline{gap:6px;flex-wrap:wrap}.physics-timeline output{font-size:11px;min-width:86px}.physics-timeline label{font-size:11px}.physics-player button{padding:10px 12px}.playback-speed{gap:5px;font-size:11px}.physics-stats{grid-template-columns:1fr 1fr;margin:16px 0;gap:10px}.physics-stats>div{padding:15px}.physics-stats dt{font-size:11px}.physics-stats dd{font-size:24px}.physics-learning{grid-template-columns:1fr}.concept-card,.physics-calculation{padding:20px}.physics-inputs{gap:18px}.physics-field-heading{flex-wrap:wrap}.physics-field input[type=number]{width:100%;text-align:left;margin-top:4px}.physics-field label{font-size:12px}.physics-field select{font-size:12px}.physics-card-heading h2{font-size:18px}.physics-page footer{padding:20px 0;margin-top:12px}.physics-page footer a{flex-basis:100%}.physics-figure svg text{font-size:18px}.physics-figure svg .svg-small{font-size:16px}.physics-figure svg .svg-large{font-size:20px}}
@media(prefers-reduced-motion:reduce){.experiment-tabs button{transition:none}}
.physics-discovery{margin:28px 0;background:#eaf3ec;padding:clamp(18px,3vw,28px);border:1px solid #d4e3d7;border-radius:18px}
@media(max-width:600px){.physics-figure svg{aspect-ratio:1.6}.physics-figure svg text{font-size:24px}.physics-figure svg .svg-small{font-size:23px}.physics-figure svg .svg-large{font-size:26px}}
.physics-discovery h2{font-size:25px;margin:8px 0}.physics-discovery p{font-size:14px;color:#526b5d;margin:0 0 20px}
.physics-catalog-controls{display:grid;grid-template-columns:minmax(140px,1fr) minmax(180px,2fr);gap:16px;margin:20px 0}.physics-catalog-controls label{display:grid;gap:8px;font-size:14px;min-width:0}.physics-catalog-controls input,.physics-catalog-controls select{width:100%;min-width:0;min-height:44px;padding:10px;border:1px solid var(--line);border-radius:8px;background:white;font:inherit}.physics-paper{margin:24px 0}.physics-paper h3{font-size:22px;margin-bottom:16px}.physics-sources{margin:24px 0;font-size:13px;line-height:1.9}.physics-sources summary{cursor:pointer;font-weight:600}.physics-sources a{overflow-wrap:anywhere}.chapter-lessons small{display:block;line-height:1.9;color:var(--muted)}
@media(max-width:600px){.physics-catalog-controls{grid-template-columns:1fr}.physics-paper .chapter-card{overflow-wrap:anywhere}}
.physics-discovery-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}
.physics-discovery-grid a{display:flex;flex-direction:column;gap:12px;background:#fff;padding:18px;border:1px solid #dce5dd;border-radius:12px;text-decoration:none;min-width:0}
.physics-discovery-grid a:hover{border-color:#338569;background:#fafcf8}.physics-discovery-grid strong{color:var(--ink);font-size:16px}.physics-discovery-grid small{font-size:12px;line-height:1.8;color:#526b5d}.discovery-action{font-size:12px;font-weight:600;margin-top:auto;padding-top:6px}
@media(max-width:850px){.physics-discovery-grid{grid-template-columns:1fr 1fr}}
@media(max-width:380px){.physics-discovery-grid{grid-template-columns:1fr}}