body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f4f4f4;
    margin: 0;
}

.container {
    text-align: center;
}

#timer {
    font-size: 4rem;
    margin-bottom: 20px;
}

button {
    font-size: 1rem;
    padding: 10px 20px;
    margin: 5px;
    border: none;
    cursor: pointer;
}

button:hover {
    background-color: #ddd;
}

#controls {
    margin-bottom: 20px;
}

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

.time-btn:hover {
    background-color: #45a049;
}

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

.modify-time-btn:hover {
    background-color: #e53935;
}