Is there a way to edit Membership CSS, so it won't break when updated?

What would be the best way to edit the subscriptions page to match my theme? Without breaking it when the plugin updates? Here is the page: http://www.vixensofink.com/bareink-vip-club/ also is there a way to have the subscription show up in a widget? I see there is a widget for subscription text, but... I don't see how it works with showing the subscription like on my signup page?... Any ideas would be helpful... thanks!