Hi brnm98105, welcome to css - and terribly sorry a response is a bit delayed.
I've tested the provided code several times and it is working as desired. That suggests you are correct that something is over-riding the css.
Have you checked the page using an inspection tool such as firebug in firefox to see what styles are actually being applied? Also have you validated? There is an unclosed element in the provided code, but I thought that was probably caused by the cut/paste into the post - but it never hurts to validate to make sure.