TOPIC: Maximenu and Cassiopeia

ok I will try to do the same scenario as you
you sent me the template zip but there is only the xml file in it, I think that you probably also have some media files ?

I tried to install your xml file for your child template but it fails ...

Oh - I am trying to send the media/template folder to you, but have been temporarily blocked (too many connections)

Will try again in 30 minutes, but all you need to do is to go to the Cassiopeia template and create a new child template - with no customisation at all - and you should still see the effect. That's how I have the site set up now.

After many investigations, I can tell for sure that Maximenu CK is not in cause
you see the problem with it because it loads some styles with padding / margin that makes the problem visible, but it occurs also with the native joomla menu, and finally all the page

Thanks so much for all your help in investigating this - I concur with your findings which have given me a good direction for further examination. I suspect this will be linked to a template package I'd installed in Joomla 3 (fontaine_j3) and not removed all unsupported elements in upgrading to Joomla 4.