Great! It's one of those "Why didn't I think of that?" ideas.
It's difficult to judge, but I'm sure it slowed me down as well so I removed it for now.
Your cache code should be $globaltemplates[] = 'npa_showthreadbit'; since it's unnecessary and inefficient to deal with an array for just one item, but that didn't help.
Incidentally, there's nothing wrong with the CSS or even the colours. It looks exactly the same on a default theme as it does in the screenshot, so I don't see the problem.