I suggest that consideration be given toward using the CSS var() Function to define variables for colors used in ectcart.css, particularly for buttons like so:

:root {
--addtocart-btn: #009966;
--checkout-btn: #f26522;
--submit-btn: #009966;
--cancel-btn: #b00000;
--askquestion-btn: #1779ba;
}

That would give Ecommerce Templates Users a simple way to edit the color scheme however desired.

Gary