How to change the font color of the add & remove labels in the configurable list widget

I was able to change the headers to the font color of my form. I have not been able to figure out how to change the Add label (which I called Next) and the Remove Label to match the color and fonts of my form.

You can use this CSS code:

button{
color: red !important;
}

How to Inject CSS Codes to Widgets  

For example, here I have changed the button text colour to red:

Thank you!