Install sass

npm install node-sass

$myRed: red;

h1 {
  color: $myRed;
}

import React from 'react';
import ReactDOM from 'react-dom';
import './mysass.scss';

class Profile extends React.Component {
  render() {
    return (
      <div>
      <h1>Hello World!</h1>
      </div>
    );
   
}
}

ReactDOM.render(<Profile />, document.getElementById('root'));