By default, this feature is not integrated into Hakyll, but a css example is present on the Github repo.
Just add this code to your stylesheet and voilà:
if syntax_color is True:
print("It works !")You can also find other styles at https://github.com/Anomareh/pygments-styles-dump, but these ones will require a little adaptation.
Edit: There is also a way to call pygmentize from hakyll: https://jip.dev/posts/the-switch-to-hakyll/