I want the canvas to be A5 (half of an A4) but I want the PDF to be a standard A4. 

Basically I want the PDF to download/print with margins but I don't want the user to see the margins in the canvas.

I tried to hide the margins via CSS but couldn't work out how to do it.

Is there a better way?

If I make the change to lower-canvas then I can see it on the screen with the online developer tool but I cannot work out what the css div is for lower-canvas. Any help will be much appreciated.