I see exactly what you are describing - if i click on a category, when I go to that page ie: home::freebies the word home has vanished into the header - the rollover makes it pop out. I am looking at your page in ff. I'm having the same issue. I settled for a selver color for now - it shows up on a white background like the categories box, and a dark background like the header, but I'm not happy with it. I'll be watching for someone's help too -
John