tools/preview/index.html (11 lines of code) (raw):
<html>
<head>
<meta charset="utf-8">
<title>React demo</title>
<link rel="stylesheet" href="/dist/main.css"></link>
</head>
<body>
<div id="root"></div>
<script src="/dist/main.bundle.js"></script>
</body>
</html>