How to change syntax highlighting in Hugo?

I am trying to change syntax highlighting for code blocks. The style is currently monokai and i want to change it to the default one. I read the documentation on the website but i still do not do it right. I set the following parameters in config.toml file but nothing changed:

PygmentsCodeFences = true
PygmentsStyle = "default"

I also generated the file syntax.css but i do not understand how should i link it and use it with my configuration. I would like to use the Chroma highlighter. I did not find highlight.js file in my theme.

Can someone provide a simple explanation with the steps I need to take? Thank you very much in advance.