Unfortunately Cassiopeia doesn't support more than one level of menus at that module position. See my issue #22930 , which I had closed not because it was solved but because a lack of interest.

I solved it for me by making a template override for the menu module. But I am not sure if I can still find it, it more than 1 year ago, maybe I have deleted it meanwhile.

@ciar4n @C-Lodder One of you both maybe has interest in making menus with more than one level useful in Cassiopeia, e.g. with dropdowns, especially in the "menu" position?

I'm disappointed ... How is it possible that 2 years later there is no solution ? How did you measure that the under menu sounds uninteresting ?

People focused a bit on the backend template ;-)

Or maybe @coolcat-creations would like to work on it?

Unfortunately I am not good in js and css stuff.

Cassiopeia seems to user only parts of Bootstrap 4, so that e.g. nav-pills also doesn't work anymore on any module position.

I found my old override now, it made it work for the "menu" module position. Was an override of the "navbar.php" file of mod_menu.

Update: Don't even find the original file anymore. Seems there has been changed much since I've made my override.

Update: I see it was an alternative layout for mod_menu, therefore the new file name.

Will see if I can find some time to work on it.

With a little handover from @C-Lodder or @ciar4n I can work on the submenu.

I think it's an important feature and obligatory to have in the frontend template, also the possibilty to add subtitles and modules in the menu to create something like a megamenu...

I heard the frontend template is css grid only, but I find bootstrap folders in the scss there, thats why I would need an intro how everything is supposed to be.

I don't want to force anyone to work on that. But many people use Joomla's default template. Association, club, etc... It's a big miss I think.

If we wanna use bs4 we just have to use special class names in the navbar area

and this is why I said we are nowhere near a beta because no one has really looked at the front end for a very long time

@Magnytu2 You do not force us to anything. You remind us, and I think we should work on that. I have a horizontal menu on my J3 private website with submenus, and I want to see that on J4 in future.

@brianteeman 100% agree: Nobody has looked on the frontent for a very long time.

That's why I play with Joomla 4 regularly.

Why closed?

Oups ...

Sorry I do not master Github at all ...

Reopened it for you.

Thanks for testing J4 and reporting.

I heard the frontend template is css grid only, but I find bootstrap folders in the scss there, thats why I would need an intro how everything is supposed to be.

The main layout of modules/component area is set using CSS grid. Everything else is still largely styled with Bootstrap. The template still looks to be loading the entire Bootstrap library so no real reason not to use https://getbootstrap.com/docs/4.0/components/navbar/

I've tried a lot of its CSS class, but nothing works. Or I didn't understand...

Looking at the html, it appears to be an issue between invalid bootstrap markup and conflicting template css.

Hello using Joomla 4 beta 1, I don't see any change. Do you have a solution please?

Please test PR #29413