Firefox specific viewing issue

I apologize in advance for where this should or shouldnt be posted. I am not sure if its a specific theme issue or not, my instinct is its just that firefox is handling things just differently enough to ruin my easy illusion.

Anyway

I have a site at https://www.theparkblogger.com and I wanted to make a black bar across the entire screen the same size as my logo. My logo was 940px X 191px

It seemed simple enough, I just created a black image that was 191px tall and tiled it horizontally, and I got the desired result I wanted. At least I did until I viewed it with firefox. It looks great in Chrome and IE but it looks like firefox wants to pad my original image so now the black box I wanted isn’t lining up.

Any suggestions how I might handle this?

Thank you anyone who takes the time to look, I appreciate it.