Widgeditor requires default CSS

I'm working on a site at the moment, and I am having an issue with widgeditor. At the moment, I am running a theme that has a black background, white nodes and black text.

Unfortunatly widgeditor uses the black background and black text, so I cannot see what I am typing in. I have tried editing the CSS files with widgeditor but have had no luck.

I'd like to see an option for widgeditor to either use the CSS from the site, or a default CSS style with a white background and black text like you get with TinyMCE.