Font Color vs. Category Color

I have an events calendar on a page for a book authors club. There are several different categories on the calendar. Some of the categories I am using a fairly light color for the category. I need a way to put a Dark color font on those categories or a dark font on all of the categories. I noticed on the calendar that the “White” color category automatically placed a black font on the category but all the other category colors are white and some do not show up well.

How can I fix?

Thanks.
Jeff

The page I need help with: [log in to see the link]