How specify button background-color as hex color in configuration

So I have some buttons defined. The functionality is good, but I was requested to make them "colorful" with some specific colors.

I tried the Class Name feature, where my class name only defined the specified background color (see attached screenshot). However, an extra margin appeared, the size and shape changed, and it appeared an em or two lower than the other default buttons.. How can I leave all the other button properties as-is (size, margin, padding, etc) but only define the background-color as I am trying to do?

dom: 'Bfrtip',
buttons: [
    {
                    extend: 'colvisGroup',
        text: 'Coordinate',
        /* backgroundColor: '#e0ffff' */

        show: [4, 5,6,7,8,9],
        hide: [10, 11, 12, 13]
    }]