After https://github.com/rails/tailwindcss-rails/commit/8af7bfcb1a11d7cd63a3be4a6a3c53a9a37df679 group-hover classes, `group-hover:text-gray-900` for example, are not purged. This adds a substantial amount of classes to the outputted css. Unfortunately my regex skills are not strong enough to fix it. (Originally created a [comment](https://github.com/rails/tailwindcss-rails/issues/15) but a new issue is probably more visible to people. )