Thanks for that Jamie,
I’ve sussed out why it wasn’t working. The top/bottom default spacing is fine, it’s only the sides of the text that I wanted to space out so I only added pixels in the ‘sides’ box. Canvas also needs an entry in the ‘top/bottom’ box to make the ‘sides’ box effective.
I haven’t yet found out why the page content has pushed downwards. I suspect there’s a renegade padding entry somewhere causing the issue although I don’t recall what I might have done. I would be most gratefull if you could point me in the right direction for anything that would give a fix.