body {
    font-family: Arial, sans-serif;
    text-align: center;
    padding-top: 50px;
}

.card {
    width: 100px;
    height: 150px;
    margin: 0 auto 20px;
    background-color: #fff;
    border: 1px solid #000;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2em;
    cursor: pointer;
    user-select: none;
    box-shadow: 0 2px 6px rgba(0,0,0,0.15);
    transition: transform 0.3s ease;
}

.back {
    background-color: #333;
    color: #fff;
}

button {
    margin: 0 10px;
    padding: 10px 20px;
    font-size: 1em;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    background-color: #007bff;
    color: white;
    transition: background-color 0.3s ease;
    user-select: none;
}

button:hover,
button:focus {
    background-color: #0056b3;
    outline: none;
}