The pdf created has an odd size of 8.26 x 11.69 inches. Most common sizes are 8.5 x 11 inches (letter) and 8.5 x 14 inches (legal).
Topic on Talk:Reading/Web/PDF Functionality/Flow
That is the metric A4 paper size, standard almost everywhere outside of the U.S.
Is it possible to get the user's default paper size from the browser? Ideally there needs to be an option for the user to choose paper size, even if the user's default is read somehow.
"Is it possible to get the user's default paper size from the browser". That's not possible.