I have set up tailwind in react app via npm based on what documentation says,there is no error but I see that only css reset codes of tailwind are working and no class works. if you know what should I do, I'll appreciate it.

app.js :

import "./styles/output.css";

const App = () => {
  return (
    <>
      <h1 className="bg-gray-200 text-xl border-4 border-red-500">
        hello world
      </h1>
      <p className="font-bold text-2xl m-5"> what are you doing ?</p>
    </>
  );
};

export default App;