Tricky question, doctype

[optikalefx]

Im making a firefox extension.  One of the features im using is the html 5 canvas.  Which had the ability to load a remote website and scale it, basically making it a thumbnail of the site.  Now my thumbnail works great on sites that dont have a doctype.  But for all of those that do, canvas wont work.  Moreover, i had my extension delete the doctype as the very first thing, but it still took affect and canvas never loaded.  so that leads me to belive, changing the doctype wont do it either.

 

so my question is a) can you think of another way, not using canvas, to load a website and scale it down or b) bypass the doctype so that it doesnt F with everything?

 

btw, all changes are not permant of course, they just affect whats happening while the extension is running.  THANKS!!