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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.container {
    width: 100%;
    max-width: 500px;
    padding: 20px;
}

.timer-card {
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    text-align: center;
}

h1 {
    color: #333;
    margin-bottom: 30px;
    font-size: 2.5rem;
    font-weight: 300;
}

.timer-display {
    position: relative;
    margin-bottom: 40px;
}

.time-display {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 3rem;
    font-weight: 300;
    color: #333;
    z-index: 2;
}

.progress-ring {
    position: relative;
    display: inline-block;
}

.progress-ring svg {
    transform: rotate(-90deg);
}

.progress-ring circle {
    transition: stroke-dashoffset 0.3s ease;
}

.timer-controls {
    margin-bottom: 30px;
}

.time-input {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
}

.time-input input {
    width: 80px;
    height: 50px;
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    text-align: center;
    font-size: 1.2rem;
    font-weight: 500;
    transition: border-color 0.3s ease;
}

.time-input input:focus {
    outline: none;
    border-color: #4CAF50;
}

.time-input span {
    font-size: 1.5rem;
    font-weight: 500;
    color: #666;
}

.buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 100px;
}

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

.btn-primary {
    background: #4CAF50;
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background: #45a049;
    transform: translateY(-2px);
}

.btn-secondary {
    background: #2196F3;
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background: #1976D2;
    transform: translateY(-2px);
}

.btn-danger {
    background: #f44336;
    color: white;
}

.btn-danger:hover:not(:disabled) {
    background: #d32f2f;
    transform: translateY(-2px);
}

.preset-buttons {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
}

.preset-btn {
    padding: 8px 16px;
    border: 2px solid #4CAF50;
    background: transparent;
    color: #4CAF50;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.preset-btn:hover {
    background: #4CAF50;
    color: white;
    transform: translateY(-1px);
}

@media (max-width: 480px) {
    .timer-card {
        padding: 30px 20px;
    }
    
    .time-display {
        font-size: 2.5rem;
    }
    
    .buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 200px;
    }
    
    .preset-buttons {
        gap: 8px;
    }
    
    .preset-btn {
        padding: 6px 12px;
        font-size: 0.8rem;
    }
}