Module class suffix 'color1' etc. not appearing correctly

The module class suffixes of 'color1', 'color2' and 'dark' do not appear to be working properly on my site.

Whenever I apply them to a menu, not only is the color (of color1 and color2) different from on the demo site, but the active link also appears highlighted and illegible.

I'm guessing this is a misconfiguration on my site somewhere, but any help would be much appreciated. Example attached.

Thanks.

Could you please provide me with a URL to your website, either here or via PM (click the “Private Message” text underneath my avatar) so that I may analyze it? It is a lot easier for us to diagnose issues when we have a live site to examine.