I made something like this, not only the header, I just dont know the right english word for it. I think it?s border or marginal not sure, I hope you understand it.
It was a small snake game arround a Website/Blog. But the customer tought it is to much. Cause this was arround the website I made a layout with a white space in the middle.
You can do this easily with iframes or Jquerry, works fine. For me I also needed to make some changes to the canvas with Jquery, without it wasnt dynamicly.
Hope I could help you a bit.