Hello, @mikeb,
Go to the Dashboard >> XSTORE >> Theme Options >> Theme Custom CSS and paste the below code there.
.et_element .mini-cart-buttons .wc-forward:not(.btn-checkout){background:red !important; color:white !important;}
Then save settings and check back to your site after clearing the browser cache.
Note: In the above code the word “red” is the background color and “white” is the text color you can change them with you want.
Regards Themes Team.