W3Schools Tryit Editor

main.jsx

index.html

Button.module.css

import { createRoot } from 'react-dom/client';
import styles from './Button.module.css';

function App() {
  return (
    <div>
      <button className={styles.mybutton}>
        My Button
      </button>
    </div>
  );
}

createRoot(document.getElementById('root')).render(
  <App />
);

<!doctype html>
<html lang="en">
  <body>
    <div id="root"></div>
    <script type="module" src="/src/main.jsx"></script>
  </body>
</html>

.mybutton {
  padding: 10px 20px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}