[SOLVED] Centring page for print friendly not working?

I have an invoice page;

And I am trying to make it printable. The issue I am having is that it is not centered because the page is 1200px wide and the content group is only 650px wide. Print view looks like this;

Is there a way to force the content group to be centred? Are there other methods of generating a print safe page?

I am also trying to convert to PDF but that is a separate problem whereby it won’t generate the image inside an iframe. Ideally I would like both ‘print-friendly’ and PDF.

I found the solution, a free plugin called PrintHtml did the job perfectly.