public/503.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta http-equiv="x-ua-compatible" content="ie=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1" />
<title>Down for Maintenance</title>
</head>
<body>
<h1>Down for Maintenance!</h1>
</body>
</html>