Firefox incompatible w/ theme?, used to work though…

I have the following theme https://themes.wordpress.net/columns/3-columns/3339/tyremonkey2-10/

I used it for a few weeks, looked fine in Firefox, and just recently it is very jumbled/messed up looking. Looks fine in IE. What is causing this? It is only on the homepage, for everywhere else it is normal (if you click on “Links” for example). I assume it’s from adding content, but I don’t understand. I really like the theme and don’t want to use another, though I have to for now.

Here is what it looks like in Firefox.
https://img243.imageshack.us/img243/5376/badzs2.png