code line highlight not working in quarto webpage

[hopezh]

As shown below, the code line highlight is not working in the qmd file of a web page project.

May I ask if the code line highlight is only working for revealjs slides?

[cderv]

May I ask if the code line highlight is only working for revealjs slides?

Yes this leverage a RevealJS feature: https://revealjs.com/code/#line-numbers-%26-highlights

Quarto documents have a slightly different feature which Code Annotation: https://quarto.org/docs/authoring/code-annotation.html
working with HTML but also PDF.