tailwind-issue-8153

To reproduce the issue:

1. Run npm i in the folder

2. Navigate to the folder /tmp/build/build_1

3. In the folder build_1, run this command (with $path = your real path to this repository folder):
   $path/tailwindcss -i tailwind.css -o tailwind.min.css --postcss (to use standalone)
   or even npx tailwindcss -i tailwind.css -o tailwind.min.css --postcss (to use standard CLI)

4. It should generate the tailwind.min.css in the folder build_1 but
   it will lacks content classes in the safelist.txt file & even
   ignore safelist classes added directly in tailwind.config.js
   (for example: flex class is not generated)

5. If you remove postcss-import from the postcss.config.js, Tailwind will generate the correct file
   (i don't know why postcss-import breaks content & safelist tho)