Header Margins Different than Body of Document

I'm trying to create a document (a template, actually) where the desire is to have the header and footer margins be smaller on both the right and left sides (i.e., they are wider, spanning more of the page). It seems like the default behavior or Pages is to align the header and footer margins to the document body margins. I can't seem to find a solution and any help is appreciated. Oh Yes, I want the different margins to persist throughout the document.