Yeah, that will be to do with the way you have positioned some of the elements on the page…most particularly the HTML structure of the header.
In general, we should put our HTML elements into the source code in the order they will appear on the page (left to right and top to bottom). In your case the header elements are all over the place and you have moved them around using positioning and margin values.
I would strongly suggest that you look at re-jigging the whole thing.
However, if you want a simple fix….I think I have narrowed it down to the ‘social’ div in the header.
The social div is, effectively, breaking out of the header and causing a scroll bar at the bottom of the page.
A quick fix is to add this…
#headerContent {
overflow: hidden; <--- add this around line 34 of your CSS file
}
