There are some things to bear in mind if you're going to implement CSS-driven menus like those explored in this project. Leaving aside wider questions like whether or not drop-down menus are a good user interface (some say yes, others no), the actual behavior of these menus should be considered.
For this reason, it is imperative that submenus at least sit adjacent to their parent list items, if not actually overlap them by a small amount. If a gap even a pixel wide appears between a menu entry and its submenu, there is a high probability that the mouse pointer will exit the hover state while moving through that gap and cause any open submenus to disappear. Such a situation would basically make it impossible to use some (or all) of the submenus.