I created a topic for this some time ago, but it seems that GD pages still have conflicts with the Divi Theme Builder, which allows you to build custom headers and footers on your site. For example, you can see the difference between a header on a GD archive page https://county10.com/events/ and how it should be and is on other pages https://county10.com/.
That seems to have helped. Is there a reason for the media query? The issue happens on mobile too. That CSS helped with the sizing, but the sticky header is still staying behind the page. I assume it is a Z-index issue, but I’m not sure how to assign a z-index to the archive pages.
To open a new support ticket, first select the relevant forum and then click the "New Post" button. Example: You need support for the core plugin? Click on Core Plugin support and click on the "New Post" Button.