public/500.html
<!DOCTYPE html>
<html>
<head>
<title>Cardslap - error</title>
<link href="/assets/application.css?body=1" media="screen" rel="stylesheet" type="text/css" />
</head>
<body>
<div class="wrapper">
<header>
<h1>Cardslap</h1>
</header>
<p>Sorry, but there's been a 500 internal server error - <a href="/">back to Cardslap</a></p>
</div>
</body>
</html>