Benuel,

This method has never been tested with D7. I'm not sure what the issue is. However, since making this post I figured out a way to accomplish this type of menu using css only. No php coding, necessary.

My new method uses n-th child pseudo selectors to space the items correctly. I'll try to write a followup post explaining how, but if you want to give it a go read here first:
http://css-tricks.com/how-nth-child-works/