body {
    background-color: #f1f1f1;
    font-family: Arial;
}

/* Create three equal columns that floats next to each other */
.column {
    display: none; /* Hide columns by default */
}

/* The "show" class is added to the filtered elements */
.show {
    display: block;
}

/* Style the buttons */
.btn {
    border: none;
    outline: none;
    padding: 12px 16px;
    background-color: white;
    cursor: pointer;
}

    /* Add a grey background color on mouse-over */
    .btn:hover {
        background-color: #ddd;
    }

    /* Add a dark background color to the active button */
    .btn.active {
        background-color: #666;
        color: white;
    }