no longer able to change header graphic for a particular page

Previously I was able to change the header image for particular pages using css, but this no longer seems to work on my website. We have a special event, with 4 pages (this year using only two of the pages since we will have a virtual event.) I would like to have a different header for those pages. 1. I've had no success in CatchAdaptive Free, and am wondering if changing the header for an individual page is easy to do in CatchAdaptive PRO? 2. If I upgrade to Catch Adaptive PRO will there be a smooth transition from the free version or will I have lots of rewriting to do? Thank you - I'll hope for a prompt reply so I can get this problem fixed right away! The main page for the event has it's own url: http://Yolojuneteenth.org. This is redirected to https://davislibraryfriends.org/YoloJuneteenth/