[nico_swd]

Taken from the source code.

<script type="text/javascript">
<!--
function log_out()
{
	ht = document.getElementsByTagName("html");
	ht[0].style.filter = "progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)";
	if (confirm('Are you sure you want to log out?'))
	{
		return true;
	}
	else
	{
		ht[0].style.filter = "";
		return false;
	}
}
//-->
</script>

This won't work on Firefox though.