.physics-shell{max-width:1100px;margin:auto;padding:24px;font-size:17px;line-height:1.8;overflow-wrap:anywhere}.physics-shell h1{font-size:clamp(1.7rem,4vw,2.6rem);line-height:1.3;margin:8px 0 15px}.physics-shell h2{font-size:1.4rem;line-height:1.4;margin:22px 0 16px}.physics-shell h3{font-size:1.1rem;line-height:1.55;margin:0}.physics-shell h4{font-size:1rem;margin:0 0 8px}.physics-shell header{max-width:850px}.physics-shell p{margin:10px 0 16px}.physics-shell [hidden]{display:none!important}.physics-shell :focus-visible{outline:3px solid var(--accent);outline-offset:4px}.kicker{font-size:.85rem;font-weight:700;color:var(--accent)}.crumb{font-size:.9rem}.stats{padding:12px 16px;background:var(--bg-alt);border-left:3px solid var(--accent)}.actions{display:flex;flex-wrap:wrap;gap:10px;margin:20px 0}.course-button{display:inline-flex;align-items:center;justify-content:center;min-height:48px;padding:9px 15px;background:var(--bg);color:var(--text);border:1px solid var(--border);border-radius:9px;font:inherit;text-decoration:none;cursor:pointer;line-height:1.5}.primary{background:var(--accent);color:var(--accent-text);border-color:var(--accent)}.course-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.course-card{display:flex;flex-direction:column;gap:10px;min-height:150px;border:1px solid var(--border);border-radius:13px;padding:18px;text-decoration:none;color:var(--text)}.course-card strong{font-size:1.08rem;line-height:1.5}.course-card>span:last-child{font-size:.85rem;color:var(--muted);margin-top:auto}.course-card:hover,.course-button:hover{border-color:var(--accent)}.course-search{margin:18px 0}.physics-shell input,.physics-shell select{font:inherit;min-height:48px;padding:10px;border:1px solid var(--border);background:var(--bg);color:var(--text);border-radius:8px;max-width:100%}.course-search input{display:block;margin-top:8px;width:100%;max-width:600px}.chapter-jump{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin:22px 0}.chapter-jump select{flex:1;min-width:0}.lab{display:grid;grid-template-columns:1fr 1fr;gap:24px;border:1px solid var(--border);background:var(--bg-alt);border-radius:15px;padding:22px;margin:20px 0}.lab h2{margin:5px 0 12px}.lab-controls label{display:flex;gap:15px;justify-content:space-between;margin-top:10px}.lab-controls input{width:100%;padding:0;border:none;accent-color:var(--accent)}.lab-controls output{white-space:nowrap;font-variant-numeric:tabular-nums}.lab-note{font-size:.9rem}.lab-result{font-weight:700}.lab-scene{align-self:center;min-width:0}.mini{max-width:480px;background:var(--bg-alt);padding:15px;border-radius:12px;margin:0 auto 20px;color:var(--accent)}.mini svg,.lab-scene svg{width:100%;display:block;max-height:220px;color:var(--accent)}.mini figcaption{font-size:.85rem;line-height:1.6;color:var(--muted);text-align:center;margin-top:8px}.lab-scene .mini{padding:0}.lab-live{font-size:.85rem}.lab-note .small{font-size:.8rem}.toc{border:1px solid var(--border);border-radius:10px;padding:0 16px;margin:16px 0}.toc summary{padding:12px 0;cursor:pointer;min-height:50px;font-weight:700}.toc a{display:inline-block;min-height:44px;padding:8px 0}.toc ol{padding-left:24px}.lesson{border:1px solid var(--border);border-radius:12px;margin:12px 0;scroll-margin-top:95px}.lesson>summary{display:flex;gap:12px;align-items:center;padding:15px;cursor:pointer;list-style:none;min-height:64px}.lesson>summary::-webkit-details-marker{display:none}.topic-no{background:var(--badge-bg);color:var(--badge-text);font-weight:700;padding:4px 9px;border-radius:8px;flex-shrink:0}.plus{margin-left:auto;color:var(--accent)}.lesson[open] .plus{transform:rotate(45deg)}.lesson[open]>summary{border-bottom:1px solid var(--border)}.lesson-body{padding:20px 24px;max-width:850px;margin:auto}.formula{border-left:4px solid var(--accent);border-radius:8px;border-top:1px solid var(--border);border-right:1px solid var(--border);border-bottom:1px solid var(--border);background:var(--bg-alt);padding:16px;margin:20px 0}.formula p{margin:0;font-weight:600}.calculation{font-variant-numeric:tabular-nums}.trap{padding:16px;border-radius:10px;background:var(--badge-bg);color:var(--badge-text);margin:20px 0}.trap p{margin:6px 0 0}.next{display:inline-flex;align-items:center;min-height:48px;padding:8px 0;font-weight:700}.check{border-bottom:1px solid var(--border);padding:4px 0}.check summary{cursor:pointer;min-height:48px;padding:12px 5px}.check p{padding:12px;background:var(--bg-alt);border-radius:8px}.sources{margin-top:25px;font-size:.95rem}
@media(max-width:700px){.physics-shell{padding:18px 16px 30px}.course-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.course-card{padding:14px;min-height:145px}.course-card strong{font-size:1rem}.chapter-jump label{width:100%}.lab{grid-template-columns:1fr;padding:18px;gap:12px}.lab-scene{order:-1}.lab-scene svg{max-height:150px}.lesson-body{padding:16px}.lesson>summary{padding:13px;gap:8px}.physics-shell h1{font-size:1.8rem}}
@media(prefers-reduced-motion:reduce){.physics-shell *{animation:none!important;transition:none!important;scroll-behavior:auto!important}}