Whitespace after code block only in Firefox, not Chrome

In the new layout system, code blocks seem to cause unwanted white space after the block.

Scroll to the bottom of my page:

https://www.bettermonroe.org/

It contains a long code block.

It looks fine on Chrome.  But on Firefox and Safari, there is a large amount of whitespace between the end of the page and the footer.

The only custom CSS I have is:
p { line-height: 1.5em; }
.form-wrapper input[type=submit]:hover { background: #0FE1FD; }

I don't have a subscription that enables custom CSS on each page.

Does anyone know how this can be fixed?

Thank you!

I added some more CSS and now it is broken in Chrome too - there's a lot of whitespace below the code block.  The CSS I added (for the whole site) is:

a:link, a:visited {
  color: #0F86FD;
  text-decoration: none;
}

a:hover, a:active {
  background-color: white;
}