Get your own React server
main.jsx
index.html
MyStyle.scss
 
import { createRoot } from 'react-dom/client';
import './MyStyle.scss';

function MyHeader() {
  return (
    <div>
    <h1>My Header 1</h1>
    <h2>My Header 2</h2>
    <h3>My Header 3</h3>
    </div>
  );
}

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>

                    
@use 'sass:color';
$myColor: red;

h1 {
  color: $myColor;
}

h2 {
  color: color.adjust($myColor, $lightness: -20%);
}

h3 {
  color: color.adjust($myColor, $lightness: 20%);
}

                    
localhost:5173