Problem

I've been using firefox browser for everything and i thought my website looked good. Well last night i decided to look at it through Internet Explorer and there was alot of stuff messed up. I fixed most of it luckily but I'm stuck. Can someone please tell me why i have dark blue lines and some are purple around all my video thumbs on every page but on firefox it is white like it's supposed to be?

Yeah I never realized it wood look different with a different browser but i seen my cached page in google and noticed the difference. Then i did some investigating because this is my 1st site. It kinda looks cool having all the thumbs have blue and purple borders but i want it white. 8,000 of my 12,000 visitors were using Internet Explorer. Hope someone here has a idea how i can fix it, lol