Theming GMap info window

Hi!
My issue may sound trivial to experienced themers, but I have a trouble with GMap info window (the one that pops up when you click on the marker): it background doesn't follow the theme style, and stays light. My theme is light text on dark background, so the text is not visible well. I've tried to override the "gmapnodelabel" class in my theme CSS, but it didn't work.

Has anyone done this kind of thing? I would appreciate the style snippet very much.

Thanks,

Vladimir