Hi

In menu item I did add CSS class for page.
But this class is not added to BODY tag.

I checked index.php of Jasmine template and there I replaced this code

$pageclass = $menuParams->get('pageclass_sfx','');

by this one:

$pageclass = $menu !== null ? $menu->getParams()->get('pageclass_sfx', '') : '';

(I took above code from Cassiopeia template)

Now pageclass is added.

Maybe you want check your J4 templates regarding this issue?

Patrick