Tailwind has a standalone CLI which can be used for the build step. I do sort of agree that it's a bit of an odd recommendation in the context of this article, but the build step can be extremely minimalistic, and another nice thing is that the results are still inspectable CSS.

I use tailwind on my personal site, which is otherwise entirely just vanilla HTML, and it doesn't feel very intrusive to run the CLI in watch mode when I'm writing styles.