Friends, there are horizontal two-level menus, which are spaced the usual list. This menu is a graphical element is an arrow that is there now is using the background-image property. The goal is to make sure that it (arrow) unfolded down when you hover on a menu item. Need to do CSS forces.

How? It is clear that you need to use transform: rotate; But what about the arrow to add it to the list another tag? Advise)