W3Schools Tryit Editor

main.jsx

index.html

MyStyle.scss

import { createRoot } from 'react-dom/client';
import './MyStyle.scss';

function MyHeader() {
  return (
    <h1>My Header</h1>
  );
}

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

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

$myColor: red;

h1 {
  color: $myColor;
}