I got this custom report (model sale.order) and i have added an the svg that is fixed to the upper right corner and an image that is fixed to the lower left corner (using header and footer), but there's still a space on all the sides. The paperformat linked already has all the margins set to 0.
i'm using the next html structure inside of a web.basic_layout:
div class header
div style = position: absolute; top: 0; right: 0;
svg
div class footer
div style = position: absolute; bottom: 0; left: 0;
img
div class page
stuff like tables