CSS to Make Membership 2 Registration Buttons Different Colors

Hello, can you please suggest CSS for Membership 2 registration buttons to make the following:

Red button, white text – upon hover change to light grey background with black text

For all of the subpages of the

http://www.suspicious0bservers.org/register-2/

By subpages I mean when you click “Sign Up”, “Register My Account”, etc.