.os-page{background:#07111f;color:#eef7fb;min-height:100vh}.os-wrap{width:min(1160px,92vw);margin:auto;padding:32px 0 72px}.os-hero{padding:64px 0 36px}.os-hero h1{font-size:clamp(2.5rem,7vw,5rem);line-height:.95;margin:.25rem 0 1rem}.os-hero p{max-width:760px;color:#aebdca;font-size:1.15rem}.lab-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(270px,1fr));gap:18px}.lab-card,.quiz-card{background:#111f30;border:1px solid #2a3b4e;border-radius:18px;padding:22px}.lab-card h2,.quiz-card h2{margin-top:0}.chip{display:inline-block;padding:.35rem .7rem;border-radius:99px;background:#00c2d7;color:#07111f;font-weight:800}.warning{border-color:#f04452;background:#2a1720}.choice{display:block;width:100%;text-align:left;margin:.6rem 0;padding:.8rem 1rem;border:1px solid #405269;border-radius:12px;background:#17283b;color:#fff;cursor:pointer}.choice:hover,.choice:focus{border-color:#00c2d7}.choice.correct{background:#153b2a;border-color:#2cc970}.choice.wrong{background:#421d28;border-color:#f04452}.feedback{min-height:2.2rem;font-weight:700}.disk{display:flex;height:90px;border-radius:12px;overflow:hidden;margin:18px 0;border:2px solid #53677e}.disk span{display:grid;place-items:center;text-align:center;padding:6px;font-weight:800}.efi{width:14%;background:#ff9f1c;color:#111}.win{width:48%;background:#2374e1}.free{width:14%;background:#34465a}.linux{width:24%;background:#9b5de5}.back{color:#00c2d7;text-decoration:none;font-weight:800}