* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --accent: #10b981;
    --accent-dark: #059669;
    --danger: #ef4444;
    --warning: #f59e0b;
    --bg-dark: #0f172a;
    --bg-card: #1e293b;
    --bg-hover: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --border: #475569;
    --gold: #fbbf24;
}
body {
    background: linear-gradient(135deg, var(--bg-dark) 0%, #1a1a2e 100%);
    color: var(--text-primary);
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px;
}
.header {
    text-align: center;
    margin-bottom: 30px;
}
.header h1 {
    font-size: 2.5rem;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 8px;
}
.header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}
.menu-container {
    background: var(--bg-card);
    border-radius: 16px;
    padding: 40px;
    border: 1px solid var(--border);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    max-width: 500px;
    width: 100%;
}
.menu-title {
    font-size: 1.5rem;
    margin-bottom: 24px;
    text-align: center;
    color: var(--text-primary);
}
.btn {
    display: block;
    width: 100%;
    padding: 16px 24px;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-bottom: 12px;
}
.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(99, 102, 241, 0.3);
}
.btn-accent {
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    color: white;
}
.btn-accent:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(16, 185, 129, 0.3);
}
.btn-secondary {
    background: var(--bg-hover);
    color: var(--text-primary);
    border: 1px solid var(--border);
}
.btn-secondary:hover {
    background: var(--border);
}
.hidden { display: none !important; }

/* Game Area */
.game-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    width: 100%;
    max-width: 900px;
}
.controls-bar {
    background: var(--bg-card);
    border-radius: 12px;
    padding: 16px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 30px;
    width: 100%;
    border: 1px solid var(--border);
    flex-wrap: wrap;
}
.speed-control {
    display: flex;
    align-items: center;
    gap: 12px;
}
.speed-control label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}
.speed-slider {
    -webkit-appearance: none;
    width: 150px;
    height: 6px;
    border-radius: 3px;
    background: var(--bg-hover);
    outline: none;
}
.speed-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary);
    cursor: pointer;
    transition: 0.2s;
}
.speed-slider::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}
.speed-value {
    background: var(--bg-hover);
    padding: 4px 12px;
    border-radius: 6px;
    font-weight: 600;
    min-width: 60px;
    text-align: center;
}
.status-indicator {
    display: flex;
    align-items: center;
    gap: 8px;
}
.status-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--accent);
    animation: pulse 2s infinite;
}
@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}
.status-dot.error { background: var(--danger); }

.arena-container {
    display: flex;
    flex-direction: row;
    gap: 30px;
    justify-content: center;
    align-items: flex-start;
}
.game-panel {
    background: var(--bg-card);
    border-radius: 16px;
    padding: 20px;
    border: 1px solid var(--border);
}
.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}
.panel-title {
    font-size: 1.1rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 8px;
}
.panel-title.ai { color: var(--danger); }
.panel-title.player { color: var(--accent); }
.panel-title .icon {
    width: 24px;
    height: 24px;
}
.score-display {
    background: var(--bg-hover);
    padding: 8px 16px;
    border-radius: 8px;
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--gold);
}
canvas {
    border-radius: 8px;
    display: block;
}
.canvas-ai {
    border: 3px solid var(--danger);
    box-shadow: 0 0 30px rgba(239, 68, 68, 0.2);
}
.canvas-player {
    border: 3px solid var(--accent);
    box-shadow: 0 0 30px rgba(16, 185, 129, 0.2);
}
.controls-hint {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-top: 12px;
}
.controls-hint kbd {
    background: var(--bg-hover);
    padding: 4px 8px;
    border-radius: 4px;
    font-family: monospace;
    margin: 0 2px;
}

/* Game Over Overlay */
.game-over-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(15, 23, 42, 0.9);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(8px);
}
.game-over-card {
    background: var(--bg-card);
    border-radius: 20px;
    padding: 40px;
    text-align: center;
    border: 1px solid var(--border);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    max-width: 400px;
}
.game-over-card h2 {
    font-size: 2rem;
    margin-bottom: 16px;
}
.game-over-card .final-scores {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin: 24px 0;
}
.final-score-item {
    text-align: center;
}
.final-score-item .label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 4px;
}
.final-score-item .value {
    font-size: 2rem;
    font-weight: 700;
}
.final-score-item .value.ai { color: var(--danger); }
.final-score-item .value.player { color: var(--accent); }

/* Feature badges */
.features {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-top: 20px;
    flex-wrap: wrap;
}
.badge {
    background: var(--bg-hover);
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 6px;
}
.badge-icon {
    width: 14px;
    height: 14px;
}

/* Countdown Overlay */
.countdown-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(15, 23, 42, 0.85);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 999;
    backdrop-filter: blur(4px);
}
.countdown-number {
    font-size: 8rem;
    font-weight: 800;
    color: var(--text-primary);
    text-shadow: 0 0 60px var(--primary);
    animation: countdownPulse 1s ease-out;
}
.countdown-number.go {
    font-size: 6rem;
    color: var(--accent);
    text-shadow: 0 0 60px var(--accent);
}
@keyframes countdownPulse {
    0% {
        transform: scale(1.5);
        opacity: 0;
    }
    50% {
        transform: scale(1);
        opacity: 1;
    }
    100% {
        transform: scale(0.8);
        opacity: 0.5;
    }
}