How to change the BG color of the Add to Cart and Online Designer/Add to cart buttons?

#add-to-cart {
 background: #000000 !important; }

#add-to-cart-cbDesigner-calc {
 background: #000000 !important; } 

*Use this and use whatever hex code that you want.

Here's how to apply the code: 

1. Login to your admin
2. Go to Storefront CMS 
3. CMS Features
4. Theme Settings
5. Custom CSS tab
6. Copy the code in blue above and paste it at the top or bottom of the "Global Custom CSS Code" box. 
7. Save/Update Layout 
8. Go to your storefront, refresh, and the 3 default images will be removed