Padding grows when scrolling

Site URL: https://hardsuitlabs.squarespace.com/careers-ges-testing

I'm on a sandbox page for my companies homepage, trying to enable a function that links a script to our own page.

The script I added is a VERY basic HTML "hey, look over here" addition:

<div id="grnhse_app"></div>
<script src="https://boards.greenhouse.io/embed/job_board/js?for=hardsuitlabs"></script>

Working with the support team at greenhouse, I was told that there is nothing in their script that could cause this. I checked with them to make extra certain this would be an issue on my page.

There is no added padding in the edited page itself, there everything shows as tightly and neat as I would want it to. 

The above code should contain nothing that explains the odd behaviour the page has: When looking at the edit area, the spacing between the job forms and the rest of the page isn't only extremely large - it grows as you scroll up and down. 

I seem unable to track down this huge blank space and the way that the blank space just grows as you scroll through the page is a mystery to me. We have no CSS code added to the site at any place that touches the margins. 

I have checked the padding options in Spacing and Site Margin following this link. Sadly, all I could do with that page was confirm that nobody had made changes to the site's basic configuration. At this point, I feel a bit at a loss.

The bahviour of growing blankspace was observed by me on the latest versions of Edge, Firefox, and Chrome.

Very grateful for any pointers on why this happens or even indeed on how I can force it to stop.