Styling the nav (wp_nav_menu)

There are a few issues that i’m having in styling my nav. I would greatly appreciate any help!

http://all-nighter.com/

1. When you hover on the category names the list of subcategories appear underneath. But when you move your mouse from the category to the subcategories they disappear. Somehow I have to increase the size of the li’s for the categories so that when you move your mouse down you’re still hovering over the li. I thought adding padding would help, but it didn’t work out. Any ideas?

2. Right now the background color for all of the nested li’s is blue as is the color of the links’ hover states. I would like each of these sub categories to have different background colors. Is there a way to apply an id to each category li and to style them individually?

Thanks!