public/fallback.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="style/main.css"/>
<title>Offline</title>
</head>
<body>
<header>
<h1>Based on webapplate</h1>
</header>
<div id="main">
<p>You are currently offline.</p>
</div>
<footer>
<ul>
<li><button id="reload" class="reload">Reload</button></li>
</ul>
</footer>
<script type="text/javascript" src="js/fallback.js"></script>
</body>
</html>