IE bugging out

So I’m going a little nuts trying to figure out whats wrong with my CSS files, but I have no idea where to start because it just such a big mess. My site is working PERFECTLY in Chrome, Firefox, etc, but Internet Explorer is just a inexplainable blocky mess.

Anyone care to spread some insight on my plight here?

You can check out the site here: https://www.scaddistrict.com