Here is the deal:
You have the submenus having the same properties with the main menu. Anything you will use will always be the same for menus and submenus.
First you need to separate these two. You have classes "first" and "active" but I do not see them in use anywhere.
So, mark your main menu "first", then have the "first" class to float:left and remove float:left from the other class.