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Note, URLs are not allowed here, so a moderator will probably be along shortly to remove it. With that said, I looked at the site, and the problem appears to be that you have an explicit height set on one of the sections in your header (zone-header). There's no good reason to have the height set on that. Instead remove that height rule (which is the equivalent of height: auto).
You also have a margin-top: -36px on one of the items in your content, which causes a little bit of it to still be covered by the navigation. And you have margin-top of 20px on your h1 which also throws off the alignment (once you remove the -36px margin).