Change the background color of Stripe plugin

-- url of the page with the problem -- : asoundidea.com
-- HikaShop version -- : 2.5.0
-- Joomla version -- : 3.4.1
-- PHP version -- : 5.4.40
-- Browser(s) name and version -- : Chrome 43.0.2357.130

Pardon my asking but i've now spent four hours looking for where to make this change.

I want to change the background color of the Stripe payment plugin (there's a conflict with the template settings and the easiest way to fix it is to change this background color from white to something darker).

This is what it looks like:

Thanks. That worked perfectly.

~Mike.