:root{--alabaster-grey:#d3d4d9;--air-force-blue:#4b88a2;--brick-red:#bb0a21;--carbon-black:#252627;--snow:#fff9fb;--color-bg:var(--carbon-black);--color-surface:#2f3133;--color-surface-soft:#333639;--color-accent:var(--air-force-blue);--color-accent-strong:#5ca3c2;--color-accent-danger:var(--brick-red);--color-text:var(--snow);--color-text-muted:var(--alabaster-grey);--color-border-subtle:#d3d4d966;--shadow-soft:0 18px 45px #000000bf;--radius-lg:18px;--radius-xl:26px;--radius-full:999px}*,:before,:after{box-sizing:border-box}html,body{margin:0;padding:0}body{background:radial-gradient(circle at top,#d3d4d929,transparent 55%),var(--color-bg);color:var(--color-text);font-family:system-ui,-apple-system,BlinkMacSystemFont,SF Pro Text,Segoe UI,sans-serif}.app-shell{justify-content:center;min-height:100vh;padding:24px 16px;display:flex}.app-container{border-radius:var(--radius-xl);width:100%;max-width:760px;box-shadow:var(--shadow-soft);background:linear-gradient(140deg,#252627fa,#252627fc);border:1px solid #d3d4d952;padding:24px 20px 28px}.app-header{justify-content:space-between;align-items:center;gap:12px;margin-bottom:16px;display:flex}.app-title{letter-spacing:.03em;font-size:1.45rem;font-weight:650}.app-subtitle{color:var(--color-text-muted);max-width:36rem;font-size:.9rem}.badge-pill{text-transform:uppercase;letter-spacing:.14em;border-radius:var(--radius-full);color:var(--color-text-muted);border:1px solid #d3d4d9b3;padding:4px 12px;font-size:.75rem}.countdown-card{border-radius:var(--radius-lg);background:radial-gradient(circle at 0 0,#4b88a242,#0000 70%);border:1px dashed #d3d4d9bf;flex-direction:column;gap:4px;margin-top:8px;padding:12px 14px;display:flex}.countdown-label{color:var(--color-text-muted);font-size:.8rem}.countdown-value{font-family:JetBrains Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,Liberation Mono,Courier New,monospace;font-size:1rem}.btn-row{flex-wrap:wrap;gap:10px;margin-top:18px;display:flex}.btn-primary,.btn-secondary{border-radius:var(--radius-full);cursor:pointer;border:0;flex:1;justify-content:center;align-items:center;gap:8px;min-width:0;padding:10px 14px;font-size:.95rem;font-weight:600;transition:transform 80ms,box-shadow 80ms,background-color .1s,border-color .1s;display:inline-flex}.btn-primary{background:linear-gradient(135deg,var(--color-accent),var(--color-accent-strong));color:var(--carbon-black);box-shadow:0 12px 30px #4b88a28c}.btn-primary:active{transform:translateY(1px)scale(.99);box-shadow:0 6px 16px #4b88a28c}.btn-secondary{color:var(--color-text);background:#2f3133f5;border:1px solid #d3d4d999}.btn-secondary:active{transform:translateY(1px)scale(.99)}.helper-text{color:var(--color-text-muted);margin-top:12px;font-size:.8rem}.quiz-header{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:8px;margin-bottom:14px;display:flex}.metric-pill{border-radius:var(--radius-full);background:#4b88a229;border:1px solid #4b88a2a6;align-items:center;gap:8px;padding:6px 11px;font-size:.8rem;display:inline-flex}.metric-label{color:var(--color-text-muted)}.metric-value{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,Liberation Mono,Courier New,monospace}.timer-value{font-weight:600}.timer-danger{color:var(--color-accent-danger)}.question-card{border-radius:var(--radius-lg);background:var(--color-surface);border:1px solid #d3d4d966;margin-top:6px;padding:14px 14px 16px}.question-text{margin-bottom:12px;font-size:1rem}.choices-list{flex-direction:column;gap:8px;display:flex}.choice-button{background:var(--color-surface-soft);width:100%;color:var(--color-text);text-align:left;cursor:pointer;border:1px solid #d3d4d980;border-radius:12px;padding:9px 11px;font-size:.95rem;transition:transform 60ms,border-color 80ms,background-color 80ms}.choice-button:hover{border-color:#d3d4d9e6;transform:translateY(-1px)}.choice-button.correct{border-color:var(--color-accent);background:linear-gradient(135deg,#4b88a233,#4b88a252)}.choice-button.wrong{border-color:var(--color-accent-danger);background:linear-gradient(135deg,#bb0a212e,#bb0a214d)}.choice-button.disabled{opacity:.65;cursor:default;transform:none}.explanation-box{color:var(--snow);background:#4b88a22e;border:1px solid #4b88a2e6;border-radius:12px;margin-top:10px;padding:10px 11px;font-size:.85rem}.quiz-footer{color:var(--color-text-muted);flex-wrap:wrap;justify-content:space-between;align-items:center;gap:8px;margin-top:14px;font-size:.8rem;display:flex}.penalty-pill{border-radius:var(--radius-full);color:var(--color-text);background:#bb0a212e;border:1px solid #bb0a21b3;padding:4px 10px;font-size:.8rem}.result-card{border-radius:var(--radius-lg);background:var(--color-surface);border:1px solid #d3d4d980;margin-top:8px;padding:14px 14px 16px}.result-title{margin-bottom:4px;font-size:1.05rem}.result-score{margin-bottom:8px;font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,Liberation Mono,Courier New,monospace}.input-row{gap:8px;margin:10px 0;display:flex}.name-input{color:var(--color-text);background:#2f3133fa;border:1px solid #d3d4d9b3;border-radius:999px;flex:1;padding:8px 12px;font-size:.9rem}.name-input::placeholder{color:var(--color-text-muted)}.error-text{color:var(--color-accent-danger);margin-top:6px;font-size:.8rem}.leaderboard-header{justify-content:space-between;align-items:baseline;gap:8px;margin-bottom:8px;display:flex}.leaderboard-table{border-collapse:collapse;width:100%;margin-top:14px;font-size:.9rem}.leaderboard-table th,.leaderboard-table td{padding:6px 4px}.leaderboard-table th{text-align:left;color:var(--color-text-muted);border-bottom:1px solid #d3d4d9b3;font-weight:500}.leaderboard-table tr:nth-child(2n){background:#2f3133d9}.leaderboard-table tr:nth-child(odd){background:#2f313399}.back-link{color:var(--color-text-muted);cursor:pointer;background:0 0;border:0;padding:0;font-size:.8rem;text-decoration:underline}@media (max-width:600px){.app-container{padding:20px 16px 22px}.app-title{font-size:1.3rem}.btn-primary,.btn-secondary{font-size:.9rem}}