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

.container {
    padding: 20px;
    background-color: white;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    border-radius: 8px;
}

.button-group {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    margin-top: 20px;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    border: none;
    border-radius: 5px;
    background-color: #007bff;
    color: white;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #0056b3;
}

#start-button {
    font-size: 24px;
    padding: 15px 30px;
    margin-top: 30px;
}

.hidden {
    display: none;
}

#time-display {
    font-size: 3em;
    color: #333;
    margin-bottom: 20px;
}

#result {
    font-size: 1.5em;
    color: #333;
    margin-top: 20px;
}