<!DOCTYPE html>
<html>
  <head>
  	<meta charset="utf-8">
    <title>Hello Electron React!</title>
  </head>
  <body>
    <div id="react-root"></div>
    <script src="../dist/bundle.js"></script>
  </body>
</html>

<!DOCTYPE html>
<html>
  <head>
  	<meta charset="utf-8">
    <title>Hello Electron React!</title>
    <link rel="stylesheet" href="../dist/main.css" />
  </head>
  <body>
    <div id="react-root"></div>
    <script src="../dist/bundle.js"></script>
  </body>
</html>

Add link to stylesheet in production env
Add link to stylesheet in production env
