Drop Down Navigation Issue with CSS

I’m trying to create a navigation bar that will have drop downs when hovered. Currently, all of the top level links are working according to my CSS, but none of the links that should be drop downs are appearing. I’ve also tested that my navigation is working with the menu I have set up in the backend, so I’m not sure why it isn’t working. Here is the link to the website: http://illuminousmarketing.net/EID/

As you can see, I’m also having an issue with the centering of my page wrapper. For some reason, Margin: 0 auto; isn’t working. I’m a WP novice, so any help that can be given would be much appreciated. I’ve searched through the codex for answers to these issues, but haven’t found my remedy yet.