public/404.html (14 lines of code) (raw):
<!DOCTYPE html>
<html>
<head>
<title>The page you were looking for doesn't exist (404)</title>
<link href="/static.css" media="screen" rel="stylesheet" type="text/css" />
</head>
<body>
<!-- This file lives in public/404.html -->
<div class="dialog">
<h1>404</h1>
<h2>The page you were looking for doesn't exist.</h2>
<p>You may have mistyped the address or the page may have moved.</p>
</div>
</body>
</html>