The article Create a Nested Menu from Scratch is pretty useful, certainly when you just can't figure out how to simply create a sublevel list (a list within a list). And indeed, even though it is possible, it clear that it ain't easy like it should. Never the less ... I'm glad I got it to work.

Slightly disappointing when your successful attempt to create a nice menu looks pretty messed up as son as you move the viewport slider to the right (even though the menu does work).

http://coffeecup.rvanheukelum.com/rsd-create-a-nested-menu-from-scratch-mobile.png

http://coffeecup.rvanheukelum.com/rsd-create-a-nested-menu-from-scratch-desktop.png

Good luck with that puppy ...