Weird text highlight when changing theme

[Zvi Twersky]

I am trying to change my theme to a dark theme. But for some reason, all of the text is getting a strange highlighted effect (but it’s not highlighted). Any ideas on how to fix this? Thanks!

[Ekopalypse]

Languages are not theme aware which means, each theme need to implement its version of the used styles.
See here for more details.