I spent way too much time on this and I can\'t figure out a good 21th century solution.
Simply I have to generate a business card in PDF with a background image, but MPD
mPDF has a custom css property for background images: background-image-resize with custom values from 0-6:
So you probably need: body {background-image:url(something.png); background-image-resize:6}
Taken from mPDF docs