Background color for markdown code block for the hugo-researcher theme

This indeed fixes the problem.
Thank you so much
I would like to choose the theme of my syntax highlighting.
I see that Hugo uses goldmark which uses goldmark-highlighting which uses chroma.
In order to change the highlighting theme, it is not clear to me where I can control this.
In this post you mention that there is no need to build goldmark-highlighting because hugo has this already.