body {
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f0f2f5;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: #333;
}

.metronome-container {
    background: white;
    padding: 2rem;
    border-radius: 24px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    text-align: center;
    width: 320px;
}

h1 {
    margin-bottom: 2rem;
    font-weight: 700;
    font-size: 1.5rem;
    color: #1a1a1a;
}

.bpm-display {
    margin-bottom: 1.5rem;
}

#bpm-value {
    font-size: 4rem;
    font-weight: 800;
    color: #007AFF;
}

.unit {
    font-size: 1.2rem;
    color: #666;
    margin-left: 5px;
}

.controls {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

button {
    cursor: pointer;
    border: none;
    transition: all 0.2s ease;
}

#decrease-bpm, #increase-bpm {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: #eee;
    font-size: 1.2rem;
    font-weight: bold;
}

#decrease-bpm:hover, #increase-bpm:hover {
    background: #ddd;
}

#bpm-slider {
    flex: 1;
    accent-color: #007AFF;
}

.primary-btn {
    width: 100%;
    padding: 1rem;
    border-radius: 12px;
    font-size: 1.2rem;
    font-weight: 600;
    background: #007AFF;
    color: white;
    margin-bottom: 2rem;
}

.primary-btn:hover {
    background: #0063d1;
    transform: translateY(-2px);
}

.primary-btn.playing {
    background: #ff3b30;
}

.primary-btn.playing:hover {
    background: #d32f2f;
}

.visualizer {
    display: flex;
    justify-content: center;
    height: 60px;
}

.indicator {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: #ddd;
    transition: transform 0.1s ease, background 0.1s ease;
}

.indicator.active {
    background: #007AFF;
    transform: scale(1.5);
    box-shadow: 0 0 15px rgba(0,122,255,0.5);
}