Tailwind CSS classes is not working in my project?

This error is due to tailwind not finding any classes to scan in what it ‘thinks’ is your HTML code directories.

This section in your tailwind.config.js file determines which files are scanned to be processed by tailwind

  content: [
    './pages/**/*.{html,js}',
    './components/**/*.{html,js}',
  ],

This corrected the issue for me.

Official documentation: https://tailwindcss.com/docs/content-configuration