I know that this is not real coding issue question but I can't find god resources about this topic.
Although there are few tutorial none of them explain in details with good example how to style dnn menu.
What is the "real world" way to style dnn navigation menu skin?
By the navigation menu I think of menu similar to this:
http://cmstutorials.org/tutorial/view/how_to_build_a_kick_butt_css3_mega_drop_down_menu
http://www.red-team-design.com/wp-content/uploads/2011/03/css3-dropdown-menu-demo.html
The secret to really learning DNN is to find a skin that looks like you want, and then modify it from there. Unfortunately Skinning tutorials never materialized for the platform (along with a lot of other documentation)