header and footer constant

I think you can achieve what you mean by adding position: fixed to the css of your footer- and header-divs

Hi Thanks for the reply. Didn’t work.

Any other suggestions?

Can you post a link to your site? We can make more specific suggestions if we can see a live site.

https://topthat.co.za/demo/engen/categories/

Basically I want the content below the header to change. I don’t want a whole new page to load when I click on a menu item.

This is doable with AJAX, but it requires some significant surgery to retrofit onto an existing WordPress theme. You may be better off hiring some help at https://jobs.wordpress.net/