How to print an entire HTML page ?

I owned a Xerox DocuPrint P8ex personal laser printer. For some reason, I cannot seem to be able to print HTML files correctly. With the portrait setting, the printer fails to print the entire page, cutting off certain amount from the right side of the screen.

It works fine with landscape settings, but I want to print the entire screen with a portrait settings.
So what's the solution to this problem.

eg. I can't print the entire Toms hardware front page with portrait settings

Thanks