Title header + header showing at the same time

I have a problem with a printing layout showing both the Title Header AND the Header at the same time on the first page. This happens after I made a sub-summary part taller (the part is set to resize based on objects within, objects that I also made taller). Any help or suggestion is appreciated.

Which version of FM?
Do you use a script to prepare the printing?
Do any of your objects overlap both parts
Is there an anchored horizontal line object below the title header?
Did you move grouped objects between both parts
I love thinkering with that stuff can you upload the layout without data?

I was running into strange things last week: On webd, fonts were not readable, seemed to be condensed and bold (double bold...)
The inspector did not tell anything, on the same Mac, in FM 18/19 no problem

I checked out the css with the utility from @Malcolm, seemed to be ok

Then, I selected another theme (it was a custom theme) - and it was working ok..

Still investigating, but there must be something wrong with the css... tested on several Mac's under different macOS (10.14 and 10.15) and under safari and chrome

What happens, if You change the theme? Did You a recover (on a copy)?

So have you resolved the issue?

It's on the ice for now. I will get back to it and report back. Thanks for the help.