BTW, text must appear between the 2 color tags for them to work ... though black doesn't show up well with the current default board theme.
I use the accessibility features, which create a black background with white letters (as well as blowing up print to about a centimeter high), though some graphics and print show up in color. Message boards which have their thread titles in dark colors result in an unreadable and almost invisible list of threads, for me. They'll be dark blue or something, against a black background.
All print within a post here seems to be showing up well. Maybe a dark color would always appear white for me. I just thought I'd throw that in as a possible thing to factor in, though. E47, if you'd succeeded in getting black print, I might not even have been able to see it. I'm just one person though.
By the way, if you're bored out of your skull, try turning on your accessibility features to the way I have them, high contrast, white-on-black, Windows extra large. It was pretty psychadelic for me when the new graphics kicked in. Be sure tro click on "full screen" under "View" though, or there won't be enough room on the screen to see anything much.