Set footer and header to edge of page

Hello!

I want to set footer and headder to an excel page (there is solid background in them) but there is always some white space left when printing. I set the margins to be 0 but this doesn't solve the problem.
I tried adjusting the margins in print Preview (show margins box in the lower right corner of the preview window) and dragged the margin handles and it doesn't let me draw past a certain point which is exactle the area where the white space is visible.

Thank you!