So change the theme.The manual is hard to look at, even with inverted color mode (qpdf). The white/black black/white contrast is too high. ...
I used to get past this with text-based documents and low-contrast color configurations on terminals, however, your use of a pdf precludes this technique.
No offence intended, but you need to pick another distro. It's obvious that the way we have structured MX doesn't suit your sensibilities. There are 99 other distros listed on Distrowatch and surely one of them is going to be a better choice for you.