Here is a small snippet to add a background color when you click a button.
Just like this:
To do that, just add the following CSS in the “advanced customization” section of your editor:
.button.button-custom:hover,.button.button-custom:active {
color: #fff;
background-color: #0099c7;
}
Obviously, you have to change the color code “#0099c7” for your own.
To get the best result, choose a color with a good contrast with your background.
Information: If you apply this modification, all buttons will be changed.