The +2 for the top isn't really needed for the original purpose as content fades out now, but visually, having the header and content spacing looks more correct.
The content is already padded enough to have the scrollbar sit on top.
Having the content change padding when the scrollbar appears gives an
unpleasent experience (especially when the scrollbar is hidden at first
but the user increases the content's height by clicking on a dropdown or
something)