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

:root {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2a2a2a;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --accent-primary: #4a9eff;
    --accent-success: #4ade80;
    --accent-warning: #fbbf24;
    --accent-danger: #ef4444;
    --border-color: #3a3a3a;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.container {
    width: 100%;
    max-width: 600px;
    background-color: var(--bg-secondary);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    font-weight: 600;
    letter-spacing: -0.5px;
}

main {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.status-message {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.95rem;
    padding: 0.75rem;
    background-color: var(--bg-primary);
    border-radius: 8px;
    min-height: 2.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.status-message.error {
    color: var(--accent-danger);
    border: 1px solid var(--accent-danger);
}

.status-message.success {
    color: var(--accent-success);
}

.tuner-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
    padding: 2rem 1rem;
    background-color: var(--bg-primary);
    border-radius: 12px;
}

.note-display {
    font-size: 6rem;
    font-weight: 700;
    letter-spacing: -2px;
    text-align: center;
    min-height: 7rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color 0.2s ease;
}

.note-display.in-tune {
    color: var(--accent-success);
}

.note-display.out-of-tune {
    color: var(--text-primary);
}

.frequency-display {
    font-size: 1.25rem;
    color: var(--text-secondary);
    font-variant-numeric: tabular-nums;
}

.cents-meter {
    width: 100%;
    max-width: 400px;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.cents-scale {
    display: flex;
    justify-content: space-between;
    color: var(--text-secondary);
    font-size: 0.85rem;
    padding: 0 0.5rem;
}

.cents-scale .mark.center {
    color: var(--text-primary);
    font-weight: 600;
}

.cents-indicator-container {
    position: relative;
    width: 100%;
    height: 8px;
    background-color: var(--bg-secondary);
    border-radius: 4px;
    overflow: hidden;
}

.cents-indicator-container::before {
    content: '';
    position: absolute;
    left: 50%;
    top: -4px;
    bottom: -4px;
    width: 2px;
    background-color: var(--text-primary);
    transform: translateX(-50%);
}

.cents-indicator {
    position: absolute;
    width: 16px;
    height: 16px;
    background-color: var(--accent-primary);
    border-radius: 50%;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    transition: left 0.1s ease, background-color 0.2s ease;
    box-shadow: 0 0 8px rgba(74, 158, 255, 0.6);
}

.cents-indicator.in-tune {
    background-color: var(--accent-success);
    box-shadow: 0 0 12px rgba(74, 222, 128, 0.8);
}

.cents-value {
    text-align: center;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    font-variant-numeric: tabular-nums;
    min-width: 4rem;
}

.controls {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.btn {
    padding: 0.75rem 2rem;
    font-size: 1rem;
    font-weight: 500;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-family: inherit;
}

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

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

.btn-primary:hover:not(:disabled) {
    background-color: #3a8eef;
    transform: translateY(-1px);
}

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

.btn-secondary:hover:not(:disabled) {
    background-color: var(--border-color);
}

footer {
    margin-top: 2rem;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.85rem;
}

/* Responsive adjustments */
@media (max-width: 600px) {
    .container {
        padding: 1.5rem;
    }
    
    header h1 {
        font-size: 1.5rem;
    }
    
    .note-display {
        font-size: 4.5rem;
        min-height: 5rem;
    }
    
    .controls {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
    }
}