body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family: Arial, sans-serif;
    background-color: #f0f0f0;
}

.stopwatch {
    text-align: center;
    background-color: #ffffff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

#display {
    font-size: 48px;
    margin-bottom: 20px;
}

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

.btn {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    border: none;
    border-radius: 5px;
    color: white;
    transition: background-color 0.3s ease;
}

.start {
    background-color: #4CAF50;
}

.stop {
    background-color: #f44336;
}

.reset {
    background-color: #2196F3;
}

.btn:hover {
    opacity: 0.8;
}