I’ve done it in the ‘Preview’ option within the Admin panel. When I switch to ‘tablet’ or ‘mobile’ view, the menu just stays put and doesn’t retract/disappear at all. I’ve just noticed, in the ‘Themes’ area, though, there is this message which I’ve copied and pasted below. I can see the actual Rock Star theme listed, but only the Child theme shows as activated:
Broken Themes
The following themes are installed but incomplete.
Name Description
Child Theme For Rock Star The parent theme is missing. Please install the ” rock-star” parent theme.