To be honest, I would consider re-structuring the whole header; putting things in the right order and using padding/margins to settle things in place rather than ANY positioning.
That’s not to say that positioning doesn’t have it’s place but overuse can lead to problems later.
I’m also confused why your logo h1 is ALL an image but your h2 isn’t. Wouldn’t it make sense to just use one image &/or actual text in the h1/h2 with the appropriate font-family. Granted the AT logo probably needs to be an image…but the rest of it…nah.
As for the navigation, I’m unsure why the background image has been applied to the ‘body’ instead of just the navigation ‘ul’.