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

:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --bg-color: #f5f7fa;
    --card-bg: #ffffff;
    --text-primary: #2c3e50;
    --text-secondary: #7f8c8d;
    --border-color: #e1e8ed;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 16px rgba(0, 0, 0, 0.15);
    --kick-color: #e74c3c;
    --snare-color: #3498db;
    --hihat-color: #f39c12;
    --bass-color: #9b59b6;
    --guitar-color: #1abc9c;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    text-align: center;
    margin-bottom: 30px;
    color: white;
}

.title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 15px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.date-info {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    font-size: 1rem;
    font-weight: 500;
    opacity: 0.9;
}

#date-display {
    font-weight: 500;
}

main {
    flex: 1;
}

/* 모드 선택 */
.mode-selector {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    justify-content: center;
}

.mode-btn {
    background: white;
    border: none;
    border-radius: 25px;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

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

.mode-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* 모드 컨텐츠 */
.mode-content {
    display: none;
    background: var(--card-bg);
    border-radius: 20px;
    padding: 30px;
    box-shadow: var(--shadow);
}

.mode-content.active {
    display: block;
}

/* 난이도 선택 */
.difficulty-selector {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    justify-content: center;
}

.difficulty-btn {
    background: #f0f0f0;
    border: none;
    border-radius: 20px;
    padding: 10px 20px;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.3s ease;
}

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

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

/* 박자 선택 */
.time-signature-selector {
    text-align: center;
    margin-bottom: 20px;
}

.time-signature-selector label {
    margin-right: 10px;
    font-weight: 600;
    color: var(--text-primary);
}

.time-signature-selector select {
    padding: 8px 15px;
    border-radius: 10px;
    border: 2px solid var(--border-color);
    font-size: 1rem;
    font-weight: 600;
}

/* BPM 컨트롤 */
.bpm-control {
    margin-bottom: 30px;
    text-align: center;
}

.bpm-control label {
    display: block;
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.bpm-control input[type="range"] {
    width: 100%;
    height: 8px;
    border-radius: 5px;
    background: #e0e0e0;
    outline: none;
    -webkit-appearance: none;
}

.bpm-control input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
}

.bpm-control input[type="range"]::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
}

/* 비트 시각화 */
.beat-visualization {
    position: relative;
    background: #f8f9fa;
    border-radius: 15px;
    padding: 20px;
    margin-bottom: 30px;
    min-height: 200px;
}

.beat-track {
    display: flex;
    align-items: center;
    margin-bottom: 15px;
    position: relative;
}

.track-label {
    width: 80px;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-primary);
}

.beat-grid {
    flex: 1;
    display: flex;
    gap: 5px;
    position: relative;
}

.beat-cell {
    flex: 1;
    height: 40px;
    background: white;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    transition: all 0.2s ease;
    position: relative;
}

.beat-cell.active {
    background: var(--hihat-color);
    border-color: var(--hihat-color);
}

.beat-track:nth-child(2) .beat-cell.active {
    background: var(--snare-color);
    border-color: var(--snare-color);
}

.beat-track:nth-child(3) .beat-cell.active {
    background: var(--kick-color);
    border-color: var(--kick-color);
}

.beat-track:nth-child(4) .beat-cell.active {
    background: var(--bass-color);
    border-color: var(--bass-color);
}

.beat-track:nth-child(5) .beat-cell.active {
    background: var(--guitar-color);
    border-color: var(--guitar-color);
}

.beat-cell.highlight {
    transform: scale(1.1);
    box-shadow: 0 0 10px rgba(102, 126, 234, 0.5);
    z-index: 10;
}

.playhead {
    position: absolute;
    top: 0;
    bottom: 0;
    width: 3px;
    background: var(--primary-color);
    z-index: 100;
    pointer-events: none;
    transition: left 0.1s linear;
    box-shadow: 0 0 10px rgba(102, 126, 234, 0.8);
}

/* 컨트롤 버튼 */
.controls {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.control-btn {
    background: white;
    border: none;
    border-radius: 25px;
    padding: 15px 30px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

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

.control-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.control-btn:active {
    transform: translateY(0);
}

.control-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* 오늘의 비트 정보 */
.today-beat-info {
    text-align: center;
    padding: 20px;
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    border-radius: 15px;
    color: white;
    margin-bottom: 20px;
}

.beat-description {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 15px;
}

.beat-controls {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
}

.share-btn {
    background: white;
    border: none;
    border-radius: 25px;
    padding: 12px 30px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.share-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.random-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border: none;
    border-radius: 25px;
    padding: 12px 30px;
    font-size: 1rem;
    font-weight: 600;
    color: white;
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.random-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
    background: linear-gradient(135deg, #5568d3 0%, #653a91 100%);
}

.random-btn:active {
    transform: translateY(0);
}

/* 루딤먼트 모드 */
.rudiment-selector {
    margin-bottom: 20px;
    text-align: center;
}

.rudiment-selector label {
    margin-right: 10px;
    font-weight: 600;
}

.rudiment-selector select {
    padding: 8px 15px;
    border-radius: 10px;
    border: 2px solid var(--border-color);
    font-size: 1rem;
    font-weight: 600;
}

.rudiment-display {
    text-align: center;
    margin: 30px 0;
    padding: 30px;
    background: #f8f9fa;
    border-radius: 15px;
}

.hand-indicator {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-bottom: 20px;
}

.hand {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    background: #e0e0e0;
    color: var(--text-secondary);
    transition: all 0.3s ease;
}

.hand.active {
    background: var(--primary-color);
    color: white;
    transform: scale(1.2);
    box-shadow: 0 0 20px rgba(102, 126, 234, 0.5);
}

.rudiment-pattern-text {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: 10px;
}

/* 템포 트레이너 모드 */
.tempo-trainer-controls {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    margin-bottom: 30px;
}

.tempo-input {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.tempo-input label {
    font-weight: 600;
    color: var(--text-primary);
}

.tempo-input input[type="number"] {
    padding: 10px;
    border-radius: 10px;
    border: 2px solid var(--border-color);
    font-size: 1rem;
    font-weight: 600;
}

.tempo-display {
    text-align: center;
    margin: 30px 0;
    padding: 30px;
    background: #f8f9fa;
    border-radius: 15px;
}

.current-bpm-display {
    font-size: 4rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.tempo-progress {
    width: 100%;
    height: 20px;
    background: #e0e0e0;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 15px;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transition: width 0.1s linear;
    border-radius: 10px;
}

.time-remaining {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

footer {
    text-align: center;
    padding: 30px 0;
    color: white;
    font-size: 0.9rem;
}

footer p {
    margin-bottom: 10px;
}

.footer-link {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: opacity 0.3s ease;
}

.footer-link:hover {
    opacity: 0.8;
    text-decoration: underline;
}

.loading {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(102, 126, 234, 0.95);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    color: white;
}

.loading.hidden {
    display: none;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 20px;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* 모바일 반응형 */
@media (max-width: 640px) {
    .container {
        padding: 15px;
    }
    
    .title {
        font-size: 2rem;
    }
    
    .mode-selector {
        flex-direction: column;
    }
    
    .mode-btn {
        width: 100%;
    }
    
    .mode-content {
        padding: 20px;
    }
    
    .beat-visualization {
        padding: 15px;
    }
    
    .track-label {
        width: 60px;
        font-size: 0.8rem;
    }
    
    .beat-cell {
        height: 30px;
    }
    
    .tempo-trainer-controls {
        grid-template-columns: 1fr;
    }
    
    .current-bpm-display {
        font-size: 3rem;
    }
    
    .hand {
        width: 60px;
        height: 60px;
        font-size: 1.5rem;
    }
    
    .rudiment-pattern-text {
        font-size: 1.5rem;
        letter-spacing: 5px;
    }
}

@media (max-width: 400px) {
    .title {
        font-size: 1.8rem;
    }
    
    .controls {
        flex-direction: column;
    }
    
    .control-btn {
        width: 100%;
    }
}