I'm seeing code samples that don't colour inside the lines on Chrome (8.0.552.224), and your H1s don't wrap well (the type is set "hard", with the ascenders of the second line coming right up to meet the bottom of the x-height baseline on the preceding line). I'd like to see a bit more whitespace before all of the in-copy headers, to tell the truth -- they look less like headers for the following section than independent bold statements right at the moment. A bit more space before (or a bit less space after -- your call) would "marry" them to the section they head a lot better. An argument could be made, too, that the typeface is a little too big for the content column width; a local copy with the body font size set to 85% is eminently more readable to this old coot (who has horrible old-man eyes) -- Verdana is really good for that -- and it really cuts down the raggedness of the right-hand side of the copy.
That's all picking nits, though -- overall I like the design. When it comes down to quibbling over typography, you gotta know that it's all that's left to complain about.