:root{--color-bg:#0f172a;--color-surface:#1e293b;--color-text:#f1f5f9;--color-text-muted:#94a3b8;--color-correct:#22c55e;--color-incorrect:#ef4444;--color-speed-bonus:#f59e0b;--color-primary:#3b82f6;--color-primary-hover:#2563eb;--border-radius:12px}*{box-sizing:border-box;margin:0;padding:0}body{background:var(--color-bg);color:var(--color-text);min-height:100vh;font-family:system-ui,-apple-system,sans-serif}#root{min-height:100vh}.app{flex-direction:column;min-height:100vh;display:flex}.app-header{justify-content:space-between;align-items:center;padding:1rem 1.5rem;display:flex}.session-timer{font-variant-numeric:tabular-nums;color:var(--color-text-muted);font-size:1.25rem}.score-display{color:var(--color-primary);font-size:1.5rem;font-weight:700}.app-main{flex-direction:column;flex:1;justify-content:center;align-items:center;padding:1rem;display:flex;position:relative}.round-container{flex-direction:column;align-items:center;gap:1.5rem;width:100%;max-width:600px;display:flex}.video-container{border-radius:var(--border-radius);background:var(--color-surface);width:100%;overflow:hidden}.video-player{border-radius:var(--border-radius);width:100%;display:block}.video-placeholder{aspect-ratio:4/3;border-radius:var(--border-radius);background:var(--color-surface);width:100%}.shimmer{background:linear-gradient(90deg, var(--color-surface) 25%, #2d3a4f 50%, var(--color-surface) 75%);background-size:200% 100%;animation:1.5s infinite shimmer}@keyframes shimmer{0%{background-position:200% 0}to{background-position:-200% 0}}.answer-grid{flex-direction:column;gap:.75rem;width:100%;display:flex}.answer-button{border:2px solid var(--color-surface);border-radius:var(--border-radius);background:var(--color-surface);color:var(--color-text);cursor:pointer;min-height:56px;padding:1rem 1.5rem;font-size:1.125rem;font-weight:600;transition:border-color .2s,background-color .2s}.answer-button:hover:not(:disabled){border-color:var(--color-primary)}.answer-button:focus-visible{outline:3px solid var(--color-primary);outline-offset:2px}.answer-button:disabled{cursor:default;opacity:.8}.answer-button.correct{background:var(--color-correct);border-color:var(--color-correct);color:#fff}.answer-button.incorrect{background:var(--color-incorrect);border-color:var(--color-incorrect);color:#fff}.answer-button.correct-reveal{border-color:var(--color-correct)}.feedback-message{border-radius:var(--border-radius);z-index:10;padding:.75rem 1.5rem;font-size:1.25rem;font-weight:700;position:absolute;top:0;left:50%;transform:translate(-50%)}.feedback-message.correct{background:var(--color-correct);color:#fff}.feedback-message.incorrect{background:var(--color-incorrect);color:#fff}.feedback-message.speed-bonus{background:var(--color-speed-bonus);color:#000;animation:.6s ease-in-out golden-pulse}@keyframes golden-pulse{0%,to{box-shadow:0 0 #f59e0b66}50%{box-shadow:0 0 20px 10px #f59e0b33}}.error-container{text-align:center;padding:2rem}.error-container p{color:var(--color-text-muted);margin-bottom:1rem}.retry-button{border-radius:var(--border-radius);background:var(--color-primary);color:#fff;cursor:pointer;border:none;padding:.75rem 1.5rem;font-size:1rem;font-weight:600}.retry-button:hover{background:var(--color-primary-hover)}.retry-button:focus-visible{outline:3px solid var(--color-primary);outline-offset:2px}.app-footer{color:var(--color-text-muted);flex-direction:column;align-items:center;gap:.25rem;padding:1rem;font-size:.875rem;display:flex}.app-footer a{color:var(--color-primary);text-decoration:none}.app-footer a:hover{text-decoration:underline}.attribution{font-size:.75rem}@media (prefers-reduced-motion:reduce){.shimmer,.feedback-message.speed-bonus{animation:none}}@media (width>=768px){.answer-grid{flex-direction:row}.answer-button{flex:1}}