Website problems running under Ubuntu Linux

I have a website that under Windows 10 and Mac OS runs fine on all browsers but has a major problem when used under Ubuntu Linux and other varieties. Can someone please check on a Linux box and see if it is behaving itself. Admittedly I am running the latest version of Parallels on an iMac so maybe it’s a Virtual Machine problem but it’s the only way I can run Linux at the moment!


But what’s the issue?

If I can get a kind soul to check the site on a Linux box preferably Ubuntu’s latest desktop it might help to isolate the issue but it completely makes a mess of the home page.
Link to video to show how it should be
and Link to video to show the problem on Ubuntu/Firefox

Sorry about the rubbish at the end of the videos, it was a bit of a rush job!

What version of Firefox is it?

Version 92.0 (64 bit)

Thanks, could you send us the project file via to

Project file sent as requested