I think you need to reconsider the value of the shopping cart widget regardless of its color.
Go behind the scenes and scroll down to marketing- shopping cart widget
Widget #1: Stand Alone Shopping Cart
This is a stand-alone shopping cart for your website. Copy and paste the "Embed Code" onto any page of your website, and the shopping cart, below, will appear. You can customize the appearance of the shopping cart using the options on the left. Click "Save Changes" to see the changes take effect.
Selection Background Color:
color chart