[Plugin: WordPress Printable Gift Certificate Plugin (WP Gift Cert)] Font Colours

On the following page the Value is white, as is the background?

What file do I edit to make the background black and all text white?

Also I am confused by the option Paypal URL: I’ve put http://www.paypal.co.uk but I get :
Access Denied

You don’t have permission to access “http://www.paypal.co.uk/” on this server.
Reference #18.6f2645f.1348415752.af30fce

Thanks
Louis

http://wordpress.org/extend/plugins/wp-gift-cert/