Assign themes for menu items?

Hi, I installed different themes. But I can't find a way to assign them to menu items. So, is it possible to assign another theme (not template layout) for different menu items? as set in user/config/system.yaml/pages/theme.
Maybe page01.home: theme: antimatter, page02.about:: theme: another
Another point: In your Demo One-Page-Site Skeleton there are no menu items in sidebar on mobile view in navigation except the home item? How can i get all items in there?

Thanks

I don't think there is a way of setting different themes for different menu items.. Anybody correct me if I'm wrong.. Not sure why you need that though. You can completely customize templates, load different css, scripts etc.. No need to switch themes..
Regarding menu - i will take a look and will let you know

It's not built in but you could easily write a plugin to override the theme config variable for a certain page.

OK, thanks. I'm a Joomla/Gantry user. Thought there would be a way to assign themes quickly like in Joomla.
But anyway GRAV is gravtastic! Came to Grav just 3 days ago.