Import third party CSS in JS file

[dirkjf]

In a new Symfony project that was created using symfony new my_project_directory --webapp, importing local CSS in a JS file like such works:

// app.js

import './github.css';

However when I try to add CSS from a third part, for example highlightJS, I get some strange behaviour:

// app.js

import 'highlight.js/styles/github.css'; // successful build, but won't work

It will only work when using import(), like so:
import('highlight.js/styles/github.css');

I would expect import to work for files in node_modules as it does for my own files and not have to use import(). Or am I missing something?

[dirkjf]

Closing this as it is not an issue with Webpack Encore, but with highlight.js.