Issue With CSS Variables and Button Background Styling

I’ve been creating a  custom element and after I launched it, I noticed that something was funky with the default button styling. They were white instead of gray.
I needed to be able to dynamically let the developer style the button that was in my Shadow DOM, and to do that you have to use CSS Variables. In Chrome (at least… I need to test other browsers) there seems to be no way to have a button with a background-color whose value is defined by a CSS Variable, even if the value of the CSS variable is ‘initial’, ‘inherit’, or something undefined, and have it appear as the default button.