Changing highlight colour

[einkuser]

I have two questions regarding the use of Onyx M92

(1) What files do I have to change and what part of it, if I want to change the highlight colour from black on white to grey on black, as it is on the Kindle?

(2) I managed to change the margins for epubs when using the 'pdf reader' app, by adding code I got to userstyle.css. However, when adding code to change the font (I even added the url source of the font), it didn't work and was wondering what code I should add?

Thanks!