:root{--bg:#0b1020;--panel:#131b31;--muted:#94a3b8;--text:#f8fafc;--accent:#7dd3fc;--ok:#86efac;--warn:#fde68a;--bad:#fca5a5;--line:#26334f}*{box-sizing:border-box}body{margin:0;background:linear-gradient(180deg,#08101f,#0b1020 30%);color:var(--text);font:16px/1.55 system-ui,-apple-system,Segoe UI,sans-serif}a{color:var(--accent);text-decoration:none}nav{position:sticky;top:0;z-index:4;background:#09111feF;border-bottom:1px solid var(--line);padding:12px 22px;display:flex;gap:18px;align-items:center;flex-wrap:wrap}.brand{font-weight:800;letter-spacing:.4px;color:white}.spacer{flex:1}.wrap{max-width:1120px;margin:auto;padding:28px 20px}.card{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:20px;margin:14px 0;box-shadow:0 12px 40px #0002}.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px}.big{font-size:2rem;font-weight:800}.muted{color:var(--muted)}.pill{display:inline-block;padding:5px 10px;border-radius:99px;background:#1e2b48;margin:3px;font-size:.88rem}button,.btn{background:#e2e8f0;color:#0f172a;border:0;border-radius:10px;padding:10px 14px;font-weight:700;cursor:pointer;display:inline-block}button.secondary,.btn.secondary{background:#1e293b;color:white;border:1px solid #334155}input,select,textarea{width:100%;background:#0b1326;color:white;border:1px solid #334155;padding:11px;border-radius:9px;margin:5px 0 12px}textarea{min-height:110px}.progress{height:11px;background:#0b1326;border-radius:99px;overflow:hidden}.progress>span{display:block;height:100%;background:#e2e8f0}.proof{border-left:4px solid #475569;padding-left:16px;margin:20px 0}.syllogism{background:#0b1326;border-radius:12px;padding:14px}.ok{color:var(--ok)}.bad{color:var(--bad)}.warn{color:var(--warn)}table{width:100%;border-collapse:collapse}th,td{text-align:left;padding:10px;border-bottom:1px solid var(--line)}.reader{font-family:Georgia,serif;font-size:1.15rem;line-height:1.8;max-width:760px;margin:auto;white-space:pre-wrap}.question{margin:18px 0;padding:16px;border:1px solid var(--line);border-radius:12px}.option{display:block;padding:7px 0}.option input{width:auto;margin-right:8px}.hero{padding:40px 0 12px}.hero h1{font-size:clamp(2rem,6vw,4rem);margin:.1em 0}.login{max-width:420px;margin:8vh auto}.metric{font-size:1.4rem;font-weight:800}.definition-agree{display:flex;justify-content:space-between;gap:12px;align-items:center}.locked{opacity:.45}.callout{border:1px dashed #64748b;padding:14px;border-radius:12px;background:#0a1428}video{width:100%;border-radius:12px;background:#000}.two{display:grid;grid-template-columns:1fr 1fr;gap:16px}@media(max-width:720px){.two{grid-template-columns:1fr}}
.reader-toolbar{display:flex;gap:8px;align-items:center;margin-bottom:18px}.inline-form{display:inline;margin:0}.compact{padding:7px 10px}.reader-head{max-width:860px;margin:0 auto 16px}.primary-source{max-width:860px;padding:34px 38px;line-height:1.9}.source-separation{max-width:860px;margin:0 auto}.reader-nav{max-width:860px;margin:22px auto;display:flex;justify-content:space-between;gap:16px}.chapter-row{display:flex;align-items:center;justify-content:space-between;gap:18px}.chapter-row h3{margin:.5rem 0}.reader code,.callout code{background:#070d19;border:1px solid var(--line);padding:2px 6px;border-radius:6px}@media(max-width:720px){.primary-source{padding:22px 18px}.chapter-row{align-items:flex-start;flex-direction:column}.reader-toolbar{flex-wrap:wrap}}
.argument-pool{display:grid;gap:8px}.drag-block{padding:10px 12px;background:#0b1326;border:1px solid #475569;border-radius:10px;cursor:grab}.drop-zone{min-height:240px;border-style:dashed}.labstage{height:220px;display:grid;place-items:start center;background:#070d19;border-radius:14px;overflow:hidden}.pendulum{transform-origin:50% -90px;padding-top:90px;font-size:2rem;animation:swing 2s ease-in-out infinite alternate}@keyframes swing{from{transform:rotate(-28deg)}to{transform:rotate(28deg)}}.bands{height:180px;border-radius:12px;border:1px solid var(--line)}

.course-map{overflow:hidden}.map-head{display:flex;justify-content:space-between;gap:20px;align-items:center}.d2-map{width:100%;min-height:265px;border:0}.next-step{border-left:4px solid var(--accent);background:linear-gradient(100deg,#13203b,#131b31)}.lesson-purpose{border-top:3px solid #7dd3fc}.pend-stage{position:relative;height:300px;place-items:initial;overflow:hidden}.pivot{position:absolute;left:50%;top:24px;width:14px;height:14px;border-radius:50%;background:#f8fafc;transform:translateX(-50%);z-index:3}.pend-arm{position:absolute;left:50%;top:31px;width:2px;height:210px;transform-origin:1px 0;will-change:transform}.string{position:absolute;left:0;top:0;width:2px;height:210px;background:#cbd5e1}.bob{position:absolute;left:-15px;top:195px;width:32px;height:32px;border-radius:50%;background:#e2e8f0;box-shadow:0 0 25px #7dd3fc55}.equilibrium{position:absolute;left:50%;top:32px;height:235px;border-left:1px dashed #334155}.lab-readout{display:flex;gap:18px;justify-content:space-between;flex-wrap:wrap;margin:12px 0}.button-row{display:flex;gap:8px;flex-wrap:wrap}.graph{width:100%;height:auto;background:#091426;border:1px solid var(--line);border-radius:12px;margin-top:16px}.slit-model{height:260px;display:grid;grid-template-columns:90px 50px 1fr 95px;align-items:center;gap:12px;background:#070d19;border-radius:14px;padding:16px;overflow:hidden}.source{font-size:.7rem;color:#7dd3fc;text-align:center}.barrier{height:210px;width:12px;background:#64748b;position:relative;justify-self:center}.barrier i{position:absolute;left:-2px;width:16px;height:16px;background:#070d19}.barrier i:first-child{top:78px}.barrier i:last-child{top:116px}.wave-field{height:220px;background:repeating-radial-gradient(circle at 0 50%,transparent 0 calc(var(--wave-gap,25px) - 2px),#7dd3fc55 calc(var(--wave-gap,25px) - 1px) var(--wave-gap,25px));opacity:.8}.screen{height:220px;border:1px solid #64748b;border-radius:8px}.reader-writing{border-left:4px solid #a78bfa}@media(max-width:760px){.map-head{align-items:flex-start;flex-direction:column}.d2-map{min-height:180px}.slit-model{grid-template-columns:50px 30px 1fr 55px;height:220px;padding:8px}.wave-field,.screen,.barrier{height:180px}}