:root{font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;color:#172e35;background:#eef4f4;font-synthesis:none;line-height:1.55;--action: #12645f;--action-hover: #0b4c48;--border: #bfd0d0;--ink: #172e35;--muted: #466267;--canvas: #eef4f4;accent-color:var(--action);caret-color:var(--action);scrollbar-color:#6c898b var(--canvas)}*{box-sizing:border-box}body{margin:0}::selection{background:#b9e0d9;color:var(--ink)}a{color:var(--action);text-underline-offset:.2em}button{font:inherit;font-weight:600;min-height:48px;padding:11px 20px;border:1px solid var(--action);border-radius:12px;background:var(--action);color:#fff;cursor:pointer;touch-action:manipulation;transition:background-color .14s ease-out,box-shadow .14s ease-out}button:hover{background:var(--action-hover)}button:active{box-shadow:inset 0 2px 4px #0003}button:focus-visible,a:focus-visible,summary:focus-visible,.table-wrap:focus-visible{outline:3px solid #b85900;outline-offset:4px}header{display:flex;align-items:center;gap:24px;flex-wrap:wrap;max-width:1440px;margin:auto;padding:20px 32px}header a{font-size:1.4rem;font-weight:750;letter-spacing:-.035em;text-decoration:none}header strong{font-size:.9rem;color:var(--muted);font-weight:500}header button{margin-left:auto;background:#fff;color:var(--action)}header button:hover{background:#dceeea}.shell{min-height:100vh}main{width:min(1440px,100%);margin:auto;padding:24px 32px 72px}.shell:has(>footer) main{padding-bottom:32px}h1{font-size:clamp(1.8rem,3.2vw,2.75rem);letter-spacing:-.035em;line-height:1.14;text-wrap:balance;margin:0;max-width:28ch}h2{font-size:1.45rem;letter-spacing:-.02em;line-height:1.3;margin:28px 0 16px;text-wrap:balance}p{max-width:72ch;margin:12px 0 20px}.lesson-intro{display:flex;align-items:flex-end;justify-content:space-between;gap:28px;margin-bottom:28px}.lesson-path{display:flex;flex-wrap:wrap;gap:16px;list-style:none;margin:0 0 3px;padding:0;font-size:.9rem;color:var(--muted)}.lesson-path li{padding:6px 0;border-bottom:2px solid transparent}.lesson-path [aria-current]{border-color:var(--action);color:var(--action);font-weight:650}.lesson-studio{display:grid;grid-template-columns:minmax(0,1.8fr) minmax(300px,1fr);align-items:start;gap:28px}.instruction,.teaching-rail{min-width:0}.media-stage{overflow:hidden;background:#10242d;border-radius:20px 20px 0 0}video{display:block;width:100%;aspect-ratio:16 / 10;object-fit:contain;background:#10242d}video::cue{font-size:1.0625rem;line-height:1.45;color:#fff;background:#10242df2}.media-toolbar{padding:16px 20px;background:#fff;border:1px solid var(--border);border-top:0;border-radius:0 0 20px 20px}.media-actions{display:flex;flex-wrap:wrap;gap:12px}.media-actions button:not(:first-child){background:#eef4f4;color:var(--action);border-color:var(--border)}.media-actions button:not(:first-child):hover{background:#dceeea}.credit{font-size:.85rem;color:var(--muted);margin:14px 0 0}.source{font-size:.9rem;color:var(--muted);margin:20px 0 12px}details{border-bottom:1px solid var(--border);padding:0 0 12px}summary{cursor:pointer;min-height:48px;padding:12px 0;color:var(--action);font-weight:600}details p{margin-top:12px}.teaching-rail{background:#fff;padding:26px;border-radius:20px;border:1px solid var(--border)}.objective{font-size:1.12rem;margin:0 0 16px}.objective strong{display:block;font-size:1.15rem;line-height:1.3;margin-bottom:12px}.stakes{color:var(--muted);font-size:.95rem;margin-bottom:24px}.watch-guidance,.checkpoint{border-top:1px solid var(--border);padding-top:24px}.watch-guidance h2,.checkpoint>h2:first-child{margin:0 0 16px}.watch-guidance p{color:var(--muted);margin-bottom:0}.checkpoint{animation:checkpoint-arrival .22s ease-out}@keyframes checkpoint-arrival{0%{opacity:.7}to{opacity:1}}.feedback{background:#e4f1ed;border-radius:12px;padding:16px}.options{display:flex;gap:12px;flex-direction:column}.options button{text-align:left;background:#fff;color:var(--ink);border-color:#8ba9a7;padding:16px}.options button:hover{background:#e4f1ed;border-color:var(--action)}footer{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;background:#fff;border-top:1px solid var(--border);padding:16px max(32px,calc((100vw - 1376px)/2));padding-bottom:max(16px,env(safe-area-inset-bottom))}footer span{color:var(--muted)}.demo-note{padding:24px 32px;border-top:1px solid var(--border);color:var(--muted);font-size:.85rem}.teacher-main{width:min(1280px,100%)}.teacher-results h1{margin-bottom:20px}.table-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:16px;background:#fff}table{border-collapse:collapse;width:100%;font-size:.95rem;font-variant-numeric:tabular-nums}caption{text-align:left;padding:20px;font-weight:600}th,td{text-align:left;vertical-align:top;padding:16px;border-bottom:1px solid var(--border)}th{background:#e4efed}tbody tr:last-child td{border-bottom:0}.block{display:block}.teacher-card{margin-top:36px;padding-top:8px;border-top:1px solid var(--border)}dl{max-width:75ch}dt{text-transform:capitalize;font-weight:650}dd{margin:4px 0 24px;color:var(--muted)}@media(max-width:1000px){.lesson-studio{grid-template-columns:minmax(0,1fr)}.lesson-intro{align-items:start;flex-direction:column;gap:16px}.teaching-rail{padding:24px}video{aspect-ratio:16 / 9}}@media(max-width:600px){header{padding:18px;gap:12px}header button{margin-left:0;width:100%}main{padding:18px 18px 48px}h1{max-width:none}.lesson-studio{gap:24px}.teaching-rail{padding:20px}.media-toolbar{padding:16px}.media-actions{flex-direction:column}footer{padding:16px 18px}footer button{width:100%}.demo-note{padding:20px 18px}}@media(prefers-reduced-motion:reduce){.checkpoint{animation:none}button{transition:none}}@media(prefers-reduced-transparency:reduce),(prefers-contrast:more){footer{background:#fff;-webkit-backdrop-filter:none;backdrop-filter:none;border-color:var(--ink)}.teaching-rail,.media-toolbar,.table-wrap,.options button{border-color:var(--ink)}.credit,.source,.stakes,.watch-guidance p,.demo-note,footer span{color:var(--ink)}}