A while ago, I wrote an article describing how you can inject a custom CSS stylesheet on SharePoint modern pages using an SPFx application extension. The code sample is now part of the SharePoint SP-Dev-Fx-Extensions repository on GitHub.

Since the article, I have been getting tons of e-mails asking all sorts of questions about the solution.

Since SPFx 1.6 was released, I took the opportunity to upgrade the solution to the latest and greatest version of the toolset. You can find the latest code on GitHub, or download the latest SharePoint package.

In this post, I’ll (hopefully) answer some questions about how to use it.