Ok, after working on this some more this evening, I've figured out which thtml template it is (topic....duh...sorry, I just didn't scroll down far enough on the file to see the field I was looking for). The class applied to that td is storypost{csscode}. Only storypost1 and storypost2 is referenced in the forumstyle.css file. Nothing happens when I change either one of those. And again, I've tried changing it in forumstyles and style.css (with the forum attributes added at the end).
So I'm still lost. I feel like I'm missing something really obvious. I'm just not sure what to check for next and I'm not coming up with anything on searches. But if it's been addressed before, I would love to be pointed in the right direction!
Thanks,
Rachael