by Jack Challenger.
Hi Kimber,
I've installed your announcement module on my Moodle (2.5) and it seems perfect. None of the problems thaht you have described, unless maybe I'm not referring to the same thing you are.
Here is a screenshot 
They also look exactly the same on hover over.
Maybe you can post a screenshot so we can see what it does on your Moodle.
Btw, FWIW, I count two classes of no-overflow in lable and one in announcement, although I can't see that being a problem. They will give the exact same effect with one or two of those classes here.