public/404.html
<!DOCTYPE html>
<html>
<head>
<title>The page you were looking for doesn't exist (404)</title>
<style type="text/css">
body { text-align: center; }
</style>
</head>
<body>
<!-- This file lives in public/404.html -->
<img src='/images/404.jpg' alt='404 - Not found'/>
<br/>
Source: <a href="https://httpcats.herokuapp.com/404">HTTP Status Cats API</a>
</body>
</html>