I am still trying to solve the real problem of Readwise Highlighter on websites with “dark mode” making highlights extremely difficult to read because it makes text black on a black background with yellow highlighter over it 
It was driving me bonkers here in particular because I can’t highlight and annotate wisdom harvested from all y’all but there’s a workaround at least in the Obsidian Forum under your user preferences you can change from the dark theme to the light theme.
If anyone has a userstyle or snippet I can swap in to override Readwise’s stylesheet that they like and is consistent I’d love to see it, I can’t quite get it right.