Inject CSS in Plugin

I am currently working on implementing a plugin which is based on custom css.
Therefore I need to inject the styles into the application. Since I am quite new to indico I am also quite clueless on how to achieve the import. I read about an inject-css function but it seems to be deprecated.
Therefore I would be delighted if someone could help me with this topic.

Thanks in advance

inject_bundle is what you’re looking for. It’s best if you check our existing plugins on GitHub for examples…

Just wondering, Search · inject_bundle · GitHub doesn’t show any examples of injecting a CSS file, only JS files. Are there examples with CSS files as well? And is it possible to inject a CSS file only in the payment process, but not to all pages of a specific type?

CSS and JS are handled the same way. Inject the bundle into the WP class that’s used on the page where you want to inject it.