index.js
index.html
mysass.scss
 

import React from 'react';
import ReactDOM from 'react-dom';
import './mysass.scss';
class MyHeader extends React.Component {
  render() {
    return (
      <div>
      <h1>Hello Style!</h1>
      <p>Add a little style!.</p>
      </div>
    );
  }
}
ReactDOM.render(<MyHeader />, document.getElementById('root'));
/*
Notice that you now have three files in your project:
'index.js', 'index.html', and 'mysass.scss'.
*/

$myColor: red;
h1 {
  color: $myColor;
}
localhost:3000