Im still getting to grips with responsive design and what I've been doing is buying templates - taking them apart to learn the whole thing but now I am trying to create a site that will have a vertical menu on the left which will expand to the right when a category is rolled over but I cant find anything like this anywhere.

So can this actually be done or is it not possible to do this - if someone could point me in the direction of a template like this I would appriate it. Ive seen a couple of wordpress ones but Im just looking for css/html

for example

menu item
menu item > >sub menu >> sub menu 1
menu item
I hope Ive made sense
thanks i nadvance