What I found when I coded my http://esolia.com site (specifically the inner pages like http://esolia.com/about) was, that menus depended on the framework you’re using, or, whatever javascript menu you chose. For my feeble brain, it was hard work to figure it out. You might get some ideas looking at:
I referred to the doc https://gohugo.io/extras/menus/, and to the materializecss (framework) documentation when I coded it.
FYI