:root{--bg: #0f172a;--card: #1e293b;--accent: #38bdf8;--accent-2: #8b5cf6;--text: #f8fafc;--muted: #94a3b8;--success: #22c55e;--danger: #ef4444}*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--text)}.container{max-width:900px;margin:0 auto;padding:2rem 1rem}.navbar{display:flex;align-items:center;justify-content:space-between;padding:1rem 2rem;background:var(--card);border-bottom:1px solid #334155}.navbar a{color:var(--text);text-decoration:none;margin-left:1.5rem;font-weight:500}.navbar a:hover{color:var(--accent)}.brand{font-size:1.5rem;font-weight:800;background:linear-gradient(90deg,var(--accent),var(--accent-2));-webkit-background-clip:text;-webkit-text-fill-color:transparent}.card{background:var(--card);border-radius:1rem;padding:1.5rem;margin-bottom:1rem;box-shadow:0 10px 30px #00000040}button,.btn{display:inline-block;border:none;border-radius:.5rem;padding:.75rem 1.25rem;font-size:1rem;font-weight:600;cursor:pointer;background:linear-gradient(90deg,var(--accent),var(--accent-2));color:#fff;text-decoration:none}button:hover,.btn:hover{opacity:.9}button:disabled{opacity:.5;cursor:not-allowed}input,select{width:100%;padding:.75rem;border-radius:.5rem;border:1px solid #334155;background:#0f172a;color:var(--text);font-size:1rem;margin-bottom:1rem}label{display:block;margin-bottom:.25rem;color:var(--muted);font-size:.9rem}.option{display:block;width:100%;text-align:left;margin-bottom:.75rem;background:#0f172a;border:1px solid #334155}.option.selected{border-color:var(--accent);background:#38bdf81a}.option.correct{border-color:var(--success);background:#22c55e1a}.option.wrong{border-color:var(--danger);background:#ef44441a}.error{color:var(--danger);margin-bottom:1rem}.leaderboard-row{display:flex;justify-content:space-between;padding:.75rem 0;border-bottom:1px solid #334155}.leaderboard-row:last-child{border-bottom:none}