.phys-lesson{--model:#111b2e;--model-line:#354158;--model-text:#e9edf5;--model-muted:#a3b0c7;--copper:#cc9067;--water:#71b5d4}.pl-header{display:flex;justify-content:space-between;gap:20px;align-items:flex-start}.pl-header h1{font:500 clamp(30px,4vw,42px)/1.15 'Fraunces',serif;margin:8px 0 14px}.pl-header p{color:#64748b;line-height:1.7;max-width:730px}.pl-tag{display:inline-block;color:var(--accent-deep);background:var(--accent-tint);border-radius:30px;padding:6px 11px;font-size:11px;white-space:nowrap}.pl-rail{display:flex;gap:8px;overflow:auto;padding:4px 2px 12px}.pl-rail button{border:1px solid #e2e8f0;background:white;border-radius:20px;padding:9px 14px;white-space:nowrap;color:#64748b;font:13px 'DM Sans',sans-serif;cursor:pointer}.pl-rail button[aria-current=step]{border-color:var(--accent);color:var(--accent-deep);background:var(--accent-tint)}.pl-grid{display:grid;grid-template-columns:minmax(0,1.45fr) minmax(280px,1fr);gap:24px;align-items:start}.pl-model{background:var(--model);color:var(--model-text);border-radius:18px;overflow:hidden}.pl-model-head{display:flex;justify-content:space-between;gap:12px;padding:22px 24px}.pl-model-head strong{font-size:15px}.pl-model svg{width:100%;display:block;aspect-ratio:720/430;font-family:'DM Sans',sans-serif}.pl-model svg text{fill:var(--model-text);font-size:16px}.pl-model svg .dim{fill:var(--model-muted);font-size:13px}.pl-model svg .large{font:500 30px 'Fraunces',serif}.pl-model svg .accent{fill:var(--accent)}.pl-model svg .drag{touch-action:none;cursor:grab;outline:none}.pl-model svg .drag:focus-visible{filter:drop-shadow(0 0 4px var(--accent))}.pl-model-controls{padding:18px 24px;display:flex;gap:12px;flex-wrap:wrap;align-items:center;border-top:1px solid var(--model-line)}.pl-model-controls label{font-size:13px;color:var(--model-muted);display:flex;gap:10px;align-items:center;flex-wrap:wrap}.pl-model-controls input[type=range]{width:min(230px,55vw);accent-color:var(--accent)}.pl-model-controls select{background:#1c2940;color:var(--model-text);border:1px solid #4a556d;border-radius:8px;padding:8px;font:inherit}.pl-model button{background:#24314a;border:1px solid #4a556d;color:var(--model-text);border-radius:8px;padding:8px 11px;font:12px 'DM Sans',sans-serif;cursor:pointer}.pl-model button:disabled{opacity:.5;cursor:default}.pl-live{border-top:1px solid var(--model-line);padding:17px 24px;font-size:14px;line-height:1.65;color:var(--model-text);min-height:77px}.pl-caveat{padding:0 24px 20px;color:var(--model-muted);font-size:11px;line-height:1.6}.pl-card{border:1px solid #e2e8f0;border-radius:16px;background:white;padding:24px}.pl-card h2{font:500 27px 'Fraunces',serif;line-height:1.2;margin:10px 0 16px}.pl-primer{display:grid;gap:9px}.pl-primer details{border-bottom:1px solid #edf0f4;padding-bottom:10px}.pl-primer summary{cursor:pointer;font-weight:600;font-size:14px}.pl-primer p{font-size:14px;color:#64748b;line-height:1.7;margin:10px 0}.pl-check{margin-top:22px}.pl-check p{color:#475569;font-size:14px;line-height:1.7}.pl-check label{display:block;font-size:13px;font-weight:600;margin:14px 0 7px}.pl-input{display:flex;gap:8px;flex-wrap:wrap}.pl-input input{flex:1;min-width:120px;width:150px;border:1px solid #cbd5e1;padding:10px;border-radius:8px;font:inherit}.pl-input select{padding:10px;border:1px solid #cbd5e1;border-radius:8px;background:white;font:inherit}.pl-btn{display:inline-block;border:1px solid #e2e8f0;border-radius:9px;padding:10px 14px;font:600 13px 'DM Sans',sans-serif;background:white;color:#334155;text-decoration:none;cursor:pointer}.pl-btn.primary{background:var(--accent);color:#fff;border-color:var(--accent)}.pl-actions{display:flex;gap:9px;flex-wrap:wrap;margin-top:16px}.pl-feedback{padding:13px;border-radius:8px;margin-top:15px;font-size:13px;line-height:1.6}.pl-feedback:empty{display:none}.pl-feedback.ok{color:#166534;background:#ecfdf3;border:1px solid #bbf7d0}.pl-feedback.no{color:#9a3412;background:#fff7ed;border:1px solid #fed7aa}.pl-worked{padding:14px;border-left:2px solid var(--accent);background:#fafafa;margin-top:14px;font-size:13px;line-height:1.8}.pl-worked:empty{display:none}.pl-bottom{display:flex;justify-content:space-between;gap:12px;align-items:center;padding:24px 0}.pl-bottom small{color:#64748b}.pl-context{margin-top:20px;font-size:14px;line-height:1.8}.pl-context summary{font-weight:600;cursor:pointer}.pl-complete{text-align:center;padding:50px 24px;background:white;border:1px solid #e2e8f0;border-radius:18px}.pl-complete .check{display:grid;place-items:center;width:70px;height:70px;border-radius:50%;color:#16a34a;background:#dcfce7;font-size:34px;margin:0 auto 20px}.pl-complete h2{font:500 32px 'Fraunces',serif}.pl-complete p{color:#64748b;line-height:1.8;max-width:620px;margin:20px auto}.phys-lesson :is(button,a,input,select,summary):focus-visible{outline:3px solid var(--accent);outline-offset:3px}.pl-choices{display:flex;gap:10px;flex-wrap:wrap}.pl-choices button{flex:1}.pl-model-controls .reading{font-family:'DM Mono',monospace;font-size:13px}@media(max-width:850px){.pl-grid{grid-template-columns:1fr}.pl-header{display:block}.pl-model svg{aspect-ratio:720/470}.pl-card{padding:20px}.pl-bottom{align-items:flex-start;flex-wrap:wrap}}@media(prefers-reduced-motion:reduce){.phys-lesson *{transition:none!important;animation:none!important}}

/* Keep the solving method visible beside every linked question. */
.pl-formula{margin:16px 0;padding:15px 17px;border-left:3px solid var(--accent);border-radius:0 10px 10px 0;background:var(--accent-tint);color:#334155;line-height:1.7}.pl-formula strong{font-size:13px}.pl-formula p{margin:7px 0;font-size:15px}.pl-model-head{flex-wrap:wrap}.pl-model-head strong{margin-right:auto}