PDF print font selection (print theming)

[xor-gate]

Describe your feature request When using the Print -> PDF feature (probably macOS supplied) the printed font can not be selected.

Additional context I'm not sure about the markdown -> pdf conversion but you are probably using HTML as intermediate file format with CSS styling. I would like to be able to control the PDF theme but this could be difficult to implement.

[qxxiao]

The printed pdf style can't be consistent with the current theme style, and a lot of theme information is lost.