application/errors/error_404.php
<html>
<head>
<title>404 Page Not Found</title>
<style type="text/css">
body {
background-color: #fff;
margin: 40px;
font-family: Lucida Grande, Verdana, Sans-serif;
font-size: 12px;
color: #000;
}
#content {
border: #999 1px solid;
background-color: #fff;
padding: 20px 20px 12px 20px;
}
h1 {
font-weight: normal;
font-size: 14px;
color: #990000;
margin: 0 0 4px 0;
}
</style>
</head>
<body>
<div id="content">
<h1><?php echo $heading; ?></h1>
<?php echo $message; ?>
</div>
</body>
</html>