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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #333;
    background: #f5f5f5;
    min-height: 100vh;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

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

.back-link {
    display: inline-block;
    color: #3498db;
    text-decoration: none;
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.back-link:hover {
    text-decoration: underline;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: #2c3e50;
}

header p {
    color: #7f8c8d;
}

.controls {
    background: white;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 2rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.add-timezone {
    display: flex;
    gap: 1rem;
    max-width: 500px;
}

.add-timezone input {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
}

.add-timezone button {
    padding: 0.75rem 1.5rem;
    background: #3498db;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    transition: background 0.2s;
}

.add-timezone button:hover {
    background: #2980b9;
}

.timezones-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.timezone-card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: relative;
}

.timezone-card.custom {
    border: 2px solid #3498db;
}

.timezone-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.timezone-name {
    font-size: 1.1rem;
    font-weight: 600;
    color: #2c3e50;
}

.remove-btn {
    background: #e74c3c;
    color: white;
    border: none;
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    opacity: 0;
    transition: opacity 0.2s;
}

.timezone-card:hover .remove-btn {
    opacity: 1;
}

.remove-btn:hover {
    background: #c0392b;
}

.time-display {
    font-size: 2.5rem;
    font-weight: 300;
    color: #2c3e50;
    margin-bottom: 0.5rem;
    font-variant-numeric: tabular-nums;
}

.date-display {
    color: #7f8c8d;
    font-size: 0.9rem;
}

.offset-display {
    color: #95a5a6;
    font-size: 0.85rem;
    margin-top: 0.5rem;
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .timezones-grid {
        grid-template-columns: 1fr;
    }
    
    .add-timezone {
        flex-direction: column;
    }
}