Anyone else having issues with the header on JAMF Nation covering part of the page?

No issue here. It may be the length of your username, but seems more like a rendering problem. I don't see a reason why the search magnifying lens would need to drop down to another row. Looks like plenty of space to contain it on the first line, as per the screenshot above.
FWIW, I use Safari to access JN. Have you taken a look to see how it renders there by chance?

So, it does look like the length of your name might be affecting things. I manually resized my Safari window down and was able to reproduce the same issue. See below:

Funny thing is, if I scale it just a little further down, it completely redoes the whole window to reflect that its too small to fit everything, like this:

So, looks like JAMF needs to fix something. No issue with dropping the search icon down to another "row", but it needs to then push the window content down to be visible if its going to do that I guess.

It shows fine in Safari, which is strange. Thanks for testing it on your end @mm2270, glad it's not just me seeing the issue.

Just wanted to revive this, because, it looks like JAMF addressed this issue quietly. I noticed a change today when getting on JN. The header tags now seems smaller and the header itself seems higher in height. Here's a screenshot of it, compare it to the one I posted above and you can see the difference.

Also, if I shorten the window width, it no longer changes and cuts anything off

and

The search icon now stays on the same row at all times. Never jumps to another row like it was doing before. So, it seems its fixed. If so, thanks JAMF!

Thanks for the update @mm2270, I see the fix too