This container element is unstyled. You can give it the styling you want. Put your contents in here, in order not to let it get mixed into the menu elements. If you decide to make a fixed menu, you'll have to give this container, with the class name '.page-content', a top padding of about 60px.
This is a very versatile menu which is made to incorporate a large number of sub-menus. Just add more categories and subnav items to the 'columns', or remove some if they are too many.
The menu can easily be transformed into a fixed top menu and to cover the whole page width. In the style sheet 'mega-styles.css' are comments about what to change to achieve this.
Download the component.