src/templates/404.html
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Page not found</title>
</head>
<body>
<h2>Oops... This page is not found.</h2>
{% include 'include/tracking.html' %}
</body>
</html>