Get your own React server
main.jsx
index.html
BlueHeader.module.css
 
import { createRoot } from 'react-dom/client';
import styles from './BlueHeader.module.css';

function App() {
  return (
    <div>
      <h1 className="myheader">
        My Header
      </h1>
    </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>

                    
:global(.myheader) {
  padding: 10px 20px;
  font-size: 50px;
  color: white;
  background-color: dodgerblue;
}

                    
localhost:5173