IE11 is being BAD

I'm styling a mail form to fit in the footer. It works on EVERYTHING except IE11, and I can't figure it out!

Here's the page:

http://rawatcreations.com/formtest2.html

In IE11, the "Join" button wraps around to a second line. In every other browser, the "Join" button appears to the right of the text input boxes.

Anyone have any ideas? I've tried a lot of things and have done some searches, but can't figure it out.

Thanks!