My header is fine in firefox but messed up in IE

I’m using the “neatness” theme with some tweaks on my website https://onelessthingaustin.com/ Everything looks great in firefox but when viewed with internet explorer the title moves in front of the image, one of the menu tabs bumps down where you can’t see it (the font is white), etc. I’ve searched google for something that works and come up empty. Please help! (the placement of the photo and contact information were by accident more than design. I’m not entirely sure how I got them there so it’s certainly possible that something is messed up in my coding. ;o)

Thanks!