Table header (e.g. university rankings) displays in front of support popup.

[domdfcoding]

On the university rankings table (here), and I assume other tables done the same way, have the <thead> element displayed above the popup from the bottom of the page asking for financial support. The support popup has zindex set to 39, but the <th> elements within the <thead> have zindex set to 9999 via a .sticky class. I don't see that class defined in this repo so it might be custom for that specific page.

Here's a screenshot.

This is with Firefox on Linux