body {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
    background-color: #f0f0f0;
    font-family: Arial, sans-serif;
}
#menu {
    text-align: center;
    margin-bottom: 20px;
}
#menu h1 {
    margin: 10px 0;
}
#menu select, #menu button, #backButton {
    margin: 5px;
    padding: 5px 10px;
    font-size: 16px;
    cursor: pointer;
}
#board {
    border: 2px solid #333;
    background-color: #228B22;
}
#message {
    margin-top: 10px;
    font-size: 24px;
    font-weight: bold;
}