:root{--bg:#0b1221;--sidebar:#101b2f;--surface:#15233a;--surface2:#1a2a42;--border:#2a3c57;--ink:#e6edf8;--muted:#9daec5;--teal:#51ddc2;--mint:#9af5e4;--purple:#b6b7ff;--amber:#ffca84;--bad:#ff969e;--font:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--font);line-height:1.65}button,input,textarea{font:inherit}button{cursor:pointer}button:focus-visible,input:focus-visible,textarea:focus-visible{outline:2px solid var(--teal);outline-offset:3px}.shell{display:grid;grid-template-columns:286px minmax(0,1fr);min-height:100vh}.sidebar{border-right:1px solid var(--border);background:var(--sidebar);padding:29px 20px;display:flex;flex-direction:column;gap:26px}.brand{display:flex;align-items:center;gap:10px;font-size:20px;font-weight:800;letter-spacing:-.5px}.brand small{font-size:10px;color:var(--teal);letter-spacing:2px}.brand-symbol{width:39px;height:39px;display:grid;place-items:center;color:#092420;background:var(--teal);border-radius:12px;font-size:25px}.muted-brand{color:var(--muted)}.overline,.eyebrow,.kicker{font-size:11px;letter-spacing:2px;font-weight:800;color:var(--teal)}.overline{margin-top:12px;color:var(--muted)}.progress-head{display:flex;justify-content:space-between;font-size:12px;color:var(--muted)}.progress-head b{color:var(--ink)}.progress-track{height:8px;border-radius:99px;background:#27334d;overflow:hidden;margin-top:12px}#progress-fill{background:linear-gradient(90deg,var(--teal),var(--purple));height:100%;width:0%;transition:width .35s}nav{display:grid;gap:6px}.lesson-nav{border:1px solid transparent;border-radius:12px;background:transparent;color:var(--muted);padding:10px 9px;display:flex;align-items:center;gap:11px;text-align:left;width:100%}.lesson-nav:hover:not(:disabled){background:var(--surface2)}.lesson-nav.selected{background:#153938;border-color:#236c62;color:#eafffc}.lesson-nav:disabled{opacity:.45;cursor:not-allowed}.lesson-index{width:31px;height:31px;flex:0 0 31px;display:grid;place-items:center;border:1px solid var(--border);border-radius:9px;font-size:12px}.lesson-nav.selected .lesson-index{color:#07302a;background:var(--teal);border-color:transparent;font-weight:800}.lesson-nav.done .lesson-index{color:var(--teal);border-color:#338779}.lesson-name{font-size:13px;line-height:1.3;font-weight:700}.lesson-name small{display:block;font-size:10px;color:var(--muted);font-weight:500;margin-top:4px}.sidebar-bottom{margin-top:auto;border-top:1px solid var(--border);padding-top:18px}.sidebar-bottom p{font-size:12px;color:var(--muted);line-height:1.6}.export-btn,.reset-btn{border:none;background:transparent;color:var(--teal);font-size:12px;padding:6px 0;display:block}.reset-btn{color:var(--muted)}.main{min-width:0}.topbar{height:72px;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 clamp(20px,4vw,68px)}.pill{font-size:12px;color:var(--muted);border:1px solid var(--border);border-radius:999px;padding:4px 12px}.main-content{max-width:960px;margin:0 auto;padding:39px clamp(20px,4vw,55px)}h1{font-size:clamp(28px,3.6vw,47px);line-height:1.16;letter-spacing:-1.5px;margin:11px 0 10px}h2{font-size:19px;letter-spacing:-.4px;margin:0 0 16px}h3{font-size:15px;margin:0 0 5px}.intro{font-size:16px;color:var(--muted);margin:0 0 20px}.meta{display:flex;gap:10px;flex-wrap:wrap}.tag{background:#20304a;border:1px solid var(--border);color:#d9e7ff;border-radius:999px;font-size:12px;padding:4px 11px}.grid{display:grid;grid-template-columns:1fr 1fr;gap:19px;margin-top:27px}.panel{padding:24px;background:var(--surface);border:1px solid var(--border);border-radius:17px}.panel.accent{background:linear-gradient(140deg,#173732,#142837)}.panel.full{grid-column:1/-1}.formula{font-size:27px;font-weight:650;line-height:1.3;color:var(--mint);letter-spacing:.1px;overflow-wrap:anywhere}.formula-note{font-size:13px;color:var(--muted)}.panel-sub{font-size:13px;color:var(--muted);margin:11px 0 0}.diagram-frame{height:174px;display:flex;align-items:center;justify-content:center}.diagram-frame svg{width:100%;height:170px;max-width:380px}.diagram-caption{text-align:center;font-size:11px;color:var(--muted);margin-top:3px}.steps{display:grid;gap:13px}.step{display:flex;gap:14px;align-items:flex-start}.step-number{flex:0 0 30px;width:30px;height:30px;border-radius:9px;display:grid;place-items:center;background:#26445b;color:var(--teal);font-weight:800;font-size:13px}.step p{font-size:13px;color:var(--muted);margin:0}.step strong{color:var(--ink)}.ml-note{border-left:3px solid var(--purple);padding:12px 16px;background:#222741;border-radius:0 10px 10px 0;font-size:14px;color:#d1d4fe}.challenge{border-color:#357e72;background:linear-gradient(155deg,#132b2c,#15233a 72%)}.challenge-title{font-size:20px;margin:7px 0}.challenge-prompt{font-size:16px;color:#d8e5f6;margin:0 0 20px}.question-label{font-size:13px;color:#c1d0e0;font-weight:650;display:block;margin:0 0 7px}input,textarea{background:#0d192b;color:var(--ink);width:100%;border:1px solid #435875;padding:12px 15px;border-radius:10px}textarea{resize:vertical;min-height:83px}input::placeholder,textarea::placeholder{color:#6e86a5}.proof-fields{display:grid;gap:12px}.actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:17px}.primary{background:var(--teal);color:#092b27;border:0;border-radius:10px;padding:12px 18px;font-size:13px;font-weight:800}.primary:hover{background:var(--mint)}.primary:disabled{opacity:.45;cursor:not-allowed}.secondary{background:#20334c;color:var(--ink);border:1px solid var(--border);border-radius:10px;padding:12px 17px;font-size:13px;font-weight:650}.response{margin-top:15px;padding:15px;border-radius:11px;border:1px solid #355c66;background:#192f3b;font-size:14px}.response.warn{border-color:#755138;background:#33271f}.response.good{border-color:#327c6d;background:#133831}.response p{margin:6px 0 0}.response h3{margin-bottom:5px}.review-check{display:flex;gap:8px;align-items:start;font-size:13px;margin-top:16px;color:var(--ink)}.review-check input{width:auto;accent-color:var(--teal);margin-top:4px}.footer{text-align:center;color:#7f90a7;font-size:11px;padding:34px 0 5px}.completed{display:inline-flex;gap:8px;align-items:center;border-radius:9px;background:#1a453c;color:var(--mint);padding:9px 12px;font-size:13px;font-weight:700;margin-top:15px}.endcap{margin-top:18px;color:var(--muted);font-size:13px}.micro{font-size:11px;color:var(--muted);margin-top:9px}.vis-label{font-size:10px;fill:#b9cbe0;font-family:var(--font)}@media(max-width:850px){.shell{grid-template-columns:minmax(0,1fr)}.sidebar{border-right:0;border-bottom:1px solid var(--border);padding:15px 18px;gap:12px}.overline,.sidebar-bottom{display:none}.brand{font-size:16px}.brand-symbol{width:33px;height:33px;font-size:21px}.progress-wrap{max-width:260px}nav{display:flex;overflow-x:auto;padding-bottom:4px}.lesson-nav{min-width:160px}.topbar{height:54px}.grid{grid-template-columns:1fr}.panel.full{grid-column:1}.main-content{padding-top:25px}.pill{font-size:10px}.formula{font-size:24px}}

.gd-controls,.lab-controls{display:grid;grid-template-columns:2fr 1fr;gap:18px;margin-top:14px}
.gd-field input[type=range],.lab-field input[type=range]{width:100%;accent-color:var(--teal)}
.gd-field select{width:100%;background:var(--surface2);color:var(--ink);border:1px solid var(--border);border-radius:10px;padding:10px}
.gd-field output,.lab-field output{color:var(--amber);font-weight:800}
.gd-scale{display:flex;justify-content:space-between;font-size:11px;color:var(--muted)}
.lr-lab button:focus-visible,.lr-lab input:focus-visible,.lab-table-wrap:focus-visible,.gd-lab button:focus-visible,.gd-lab input:focus-visible,.gd-lab select:focus-visible,.gd-table-wrap:focus-visible{outline:2px solid var(--amber);outline-offset:2px}
.gd-charts{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:14px}
.gd-lab,.lr-lab{min-width:0}
.gd-charts figure{margin:0;min-width:0}
.gd-charts svg{width:100%;max-width:100%;height:auto;display:block}
.gd-table-wrap,.lab-table-wrap{max-height:190px;overflow:auto;margin-top:12px;border:1px solid var(--border);border-radius:10px}
.gd-table,.lab-table{width:100%;border-collapse:collapse;font-variant-numeric:tabular-nums;font-size:13px}
.gd-table caption,.lab-table caption{text-align:left;padding:6px 10px;margin:0}
.gd-table th,.gd-table td,.lab-table th,.lab-table td{padding:5px 10px;text-align:right;border-top:1px solid var(--border)}
.gd-table th,.lab-table th{position:sticky;top:0;background:var(--surface2);color:var(--muted)}
.gd-table tr.current td{color:var(--amber);font-weight:700}
@media(max-width:850px){.gd-controls,.gd-charts,.lab-controls{grid-template-columns:1fr}}
@media(max-width:480px){.main-content{padding-left:14px;padding-right:14px}.panel{padding:18px 16px}.vis-label{font-size:14px}.vis-label tspan{font-size:.75em}.gd-table th,.gd-table td,.lab-table th,.lab-table td{padding:5px 5px}.gd-charts svg,.lr-chart svg{overflow:visible}}

.lab-controls{grid-template-columns:1fr 1fr}
.lr-chart{margin:14px 0 0;min-width:0}
.lr-chart svg{width:100%;max-width:560px;height:auto;display:block;margin:0 auto}
.topbar{height:auto;min-height:72px;gap:12px;padding-top:8px;padding-bottom:8px}
.save-info{display:flex;flex-direction:column;align-items:flex-end;gap:3px;text-align:right}
.storage-note{font-size:11px;color:var(--muted);line-height:1.3}
.footer p{margin:2px 0}
@media(max-width:850px){.topbar{min-height:54px}.lab-controls{grid-template-columns:1fr}}
@media(max-width:480px){.topbar{flex-direction:column;align-items:flex-start;justify-content:center;gap:6px;padding-top:10px;padding-bottom:10px}.save-info{align-items:flex-start;text-align:left}}