:root{--bg:#0f172a;--panel:#111827;--card:#1f2937;--text:#e5e7eb;--muted:#94a3b8;--accent:#38bdf8;--good:#22c55e;--bad:#ef4444;--border:#334155}*{box-sizing:border-box}body{margin:0;background:linear-gradient(135deg,#020617,#111827);color:var(--text);font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}a{color:inherit}button,input,select{font:inherit}.container{width:min(1080px,calc(100% - 32px));margin:0 auto}.header{padding:28px 0;border-bottom:1px solid var(--border);background:rgba(15,23,42,.92);position:-webkit-sticky;position:sticky;top:0;z-index:10}.header h1{margin:0;font-size:clamp(1.6rem,4vw,2.6rem)}.header p{margin:8px 0 0;color:var(--muted)}.grid{display:grid;grid-gap:16px;gap:16px}.grid-3{grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}.card{background:rgba(17,24,39,.92);border:1px solid var(--border);border-radius:18px;padding:20px}.badge{display:inline-flex;align-items:center;border:1px solid var(--border);border-radius:999px;padding:4px 10px;color:var(--muted);font-size:.9rem}.btn{border:1px solid #0284c7;background:#075985;color:#fff;border-radius:12px;padding:10px 14px;cursor:pointer;font-weight:700}.btn.secondary{background:#1f2937;border-color:#475569}.choice{width:100%;text-align:left;border:1px solid #475569;background:#0f172a;color:var(--text);border-radius:12px;padding:12px;cursor:pointer}.choice.selected{outline:3px solid var(--accent)}.choice.correct{border-color:var(--good);background:rgba(34,197,94,.12)}.choice.incorrect{border-color:var(--bad);background:rgba(239,68,68,.12)}.feedback{border:1px solid var(--border);border-radius:12px;padding:14px;background:#020617;margin-top:14px}.feedback.good{border-color:var(--good)}.feedback.bad{border-color:var(--bad)}.controls{display:grid;grid-gap:12px;gap:12px;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));align-items:end}label{color:var(--muted);display:block;margin-bottom:6px}input,select{width:100%;border:1px solid #475569;background:#020617;color:var(--text);border-radius:12px;padding:10px}main{padding:24px 0 48px}.row{display:flex;flex-wrap:wrap;gap:10px}.row>*{flex:1 1 160px}.progress{height:12px;border:1px solid var(--border);background:#020617;border-radius:999px;overflow:hidden}.progress>div{height:100%;background:var(--accent);transition:width .2s}.table-wrap{overflow-x:auto}table{width:100%;border-collapse:collapse}td,th{border-bottom:1px solid var(--border);padding:10px;text-align:left}.kbd{display:inline-block;border:1px solid var(--border);background:#020617;border-radius:8px;padding:2px 8px}.muted{color:var(--muted)}.stat{font-size:2rem;font-weight:800;margin:0}.flashcard{min-height:220px;display:grid;place-items:center;text-align:center;cursor:pointer}.flashcard strong{font-size:clamp(1.5rem,4vw,2.4rem)}.flashcard .badge+.badge{margin-left:8px}.flashcard-details dl{display:grid;grid-template-columns:auto 1fr;grid-gap:8px 14px;gap:8px 14px;margin:18px 0 0;text-align:left}.flashcard-details dt{color:var(--muted);font-weight:700;text-transform:capitalize}.flashcard-details dd{margin:0}.metric-card{background:rgba(17,24,39,.92);border:1px solid var(--border);border-radius:18px;padding:20px}.metric-card span{color:var(--muted)}