PostCSS 8 for end users code example

Example: error: postcss plugin tailwindcss requires postcss 8.

yarn remove tailwindcss postcss autoprefixer
yarn add tailwindcss@npm:@tailwindcss/postcss7-compat @tailwindcss/postcss7-compat postcss@^7 autoprefixer@^9

# For zsh:
yarn add "tailwindcss@npm:@tailwindcss/postcss7-compat" "@tailwindcss/postcss7-compat" "postcss@^7 autoprefixer@^9"