Gap on page in Chrome

Hi everyone,
First of all, thanks for taking the time to look at my question.
I have been asked to help with small css/html/javascript changes on a site that was recently launched. I have made quite a few changes which were fine, but all of the sudden there is a huge gap on a page in google chrome which was not there before.
https://www.diettv.com/register.php
Does anyone have any ideas why this would be, and what I can do to fix it?
Thanks again.