Font and background of of generated PDF greyish

[Brainshack]

Hello,
from the very simple HTML that I generated PDF with, using v3 of Athena, the color of the background and the normal font is slightly off. It appears to be grey, and not like I would expect black on white background.

See: https://759b7.s3.eu-central-1.amazonaws.com/pdf/5b6071ecd83268.70933292.pdf

This is the HTML:
https://pastebin.com/eV6n8ZiF

[Brainshack]

This seems to be a CSS issue. The default styles of the PDF Generator seem to be a bit off. When I overwrite styles with a high specificity, I can get them to render in the right color. This is a workarround. Would love to know how to fix this permanently though.