:root {
    --primary: #3b82f6;
    --secondary: #8b5cf6;
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --sensor1-color: #ef4444;  /* Red for left player */
    --sensor2-color: #3b82f6;  /* Blue for right player */
    --cooperation-color: #8b5cf6; /* Purple for cooperation */
    --background: #0f172a;
    --surface: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --border: #475569;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    overflow: hidden;
    height: 100vh;
}

#gameCanvas {
    display: block;
    width: 100vw;
    height: 100vh;
    background: linear-gradient(135deg, #0f172a, #1e293b);
}

.game-ui {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
    z-index: 100;
}

.ui-panel {
    position: absolute;
    background: rgba(30, 41, 59, 0.9);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    padding: 1.25rem;
    backdrop-filter: blur(12px);
    pointer-events: all;
}

.session-panel {
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    min-width: 350px;
    max-width: 90vw;
    max-height: 90vh;
    width: auto;
    overflow-y: auto;
}

.session-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    background: linear-gradient(135deg, var(--sensor1-color), var(--sensor2-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.session-code {
    font-size: 2.5rem;
    font-weight: 700;
    font-family: 'Courier New', monospace;
    color: var(--primary);
    margin: 1rem 0;
    padding: 0.75rem;
    background: rgba(59, 130, 246, 0.1);
    border: 2px solid var(--primary);
    border-radius: 0.75rem;
    letter-spacing: 0.3em;
}

.qr-container {
    margin: 1rem 0;
    padding: 0.75rem;
    background: white;
    border-radius: 0.75rem;
    display: inline-block;
}

.sensor-status {
    display: flex;
    gap: 2rem;
    justify-content: center;
    margin: 2rem 0;
}

.sensor-info {
    padding: 1rem;
    border-radius: 0.5rem;
    min-width: 150px;
    text-align: center;
    border: 2px solid;
}

.sensor1 {
    border-color: var(--sensor1-color);
    background: rgba(239, 68, 68, 0.1);
}

.sensor2 {
    border-color: var(--sensor2-color);
    background: rgba(59, 130, 246, 0.1);
}

.sensor-label {
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.sensor-state {
    font-size: 0.9rem;
    opacity: 0.8;
}

.game-stats {
    position: absolute;
    top: 1rem;
    left: 1rem;
    display: grid;
    gap: 1rem;
    min-width: 200px;
}

.stat-item {
    background: rgba(30, 41, 59, 0.8);
    padding: 0.75rem;
    border-radius: 0.5rem;
    border: 1px solid var(--border);
    text-align: center;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.stat-value {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--primary);
}

.cooperation-meter {
    position: absolute;
    top: 1rem;
    right: 1rem;
    width: 200px;
}

.meter-label {
    text-align: center;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--cooperation-color);
}

.meter-bar {
    height: 20px;
    background: rgba(139, 92, 246, 0.2);
    border-radius: 10px;
    overflow: hidden;
    border: 1px solid var(--cooperation-color);
}

.meter-fill {
    height: 100%;
    width: 100%;
    background: linear-gradient(90deg, var(--sensor1-color), var(--cooperation-color), var(--sensor2-color));
    transition: width 0.3s ease;
}

.control-panel {
    bottom: 1rem;
    left: 1rem;
}

.control-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-template-rows: 1fr 1fr;
    gap: 0.75rem;
    width: 280px;
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 0.5rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-block;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.btn-primary {
    background: var(--primary);
    color: white;
}

.btn-secondary {
    background: var(--surface);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

.btn:hover {
    transform: translateY(-2px);
}

.hidden {
    display: none !important;
}

.game-instructions {
    position: absolute;
    bottom: 1rem;
    right: 1rem;
    max-width: 300px;
    font-size: 0.9rem;
    background: rgba(30, 41, 59, 0.8);
    padding: 1rem;
    border-radius: 0.5rem;
    border: 1px solid var(--border);
}

.instruction-title {
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--cooperation-color);
}

.instruction-item {
    margin-bottom: 0.5rem;
    padding-left: 1rem;
    position: relative;
}

.instruction-item::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary);
}

/* 🎵 음악 선택 UI 스타일 */
.music-selection {
    margin: 1rem 0;
    padding: 0.75rem;
    background: rgba(30, 41, 59, 0.5);
    border-radius: 0.5rem;
    border: 1px solid var(--border);
}

.music-title {
    text-align: center;
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--primary);
}

.music-tracks {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.6rem;
    margin-bottom: 0.75rem;
    max-height: 14rem;
    overflow-y: auto;
    padding: 0.2rem;
}

.track-option {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 0.5rem 0.4rem;
    background: rgba(30, 41, 59, 0.8);
    border: 2px solid transparent;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    height: 4rem;
    width: 100%;
    box-sizing: border-box;
}

.track-option:hover {
    background: rgba(59, 130, 246, 0.1);
    border-color: var(--primary);
    transform: translateY(-2px);
}

.track-option.selected {
    background: rgba(59, 130, 246, 0.2);
    border-color: var(--primary);
    box-shadow: 0 0 15px rgba(59, 130, 246, 0.3);
}

.track-icon {
    font-size: 1.2rem;
    margin-bottom: 0.15rem;
}

.track-name {
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--text-primary);
    text-align: center;
    margin-bottom: 0.1rem;
    line-height: 1;
}

.track-details {
    font-size: 0.6rem;
    color: var(--text-secondary);
    text-align: center;
    line-height: 1;
}

.track-status {
    position: absolute;
    top: 0.2rem;
    right: 0.2rem;
    font-size: 0.8rem;
    color: var(--success);
}

.selected-track-info {
    text-align: center;
    padding: 0.4rem;
    background: rgba(59, 130, 246, 0.1);
    border-radius: 0.4rem;
    font-size: 0.75rem;
    border: 1px solid var(--primary);
    color: var(--primary);
    font-weight: 600;
}

#selectedTrackName {
    color: var(--success);
}

/* 음악 트랙 스크롤바 스타일 */
.music-tracks::-webkit-scrollbar {
    width: 4px;
}

.music-tracks::-webkit-scrollbar-track {
    background: rgba(30, 41, 59, 0.3);
    border-radius: 2px;
}

.music-tracks::-webkit-scrollbar-thumb {
    background: var(--primary);
    border-radius: 2px;
}

.music-tracks::-webkit-scrollbar-thumb:hover {
    background: var(--secondary);
}

/* 반응형 디자인 */
@media (max-width: 480px) {
    .music-tracks {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.5rem;
        max-height: 16rem;
        padding: 0.3rem;
    }
    
    .track-option {
        height: 4.5rem;
        padding: 0.6rem 0.4rem;
    }
    
    .track-icon {
        font-size: 1.4rem;
    }
    
    .track-name {
        font-size: 0.75rem;
    }
}

@media (max-width: 360px) {
    .music-tracks {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.4rem;
        padding: 0.2rem;
    }
    
    .track-option {
        height: 4.2rem;
        padding: 0.5rem 0.3rem;
    }
    
    .track-name {
        font-size: 0.7rem;
    }
    
    .track-details {
        font-size: 0.55rem;
    }
}