<script>
var d_h=document.documentElement.scrollHeight;
set_h=(d_h-90)/2;
$(document).ready(function(){
$("#document_height").css("margin-top",set_h);
});
</script>
<script>
var d_h=document.documentElement.scrollHeight;
set_h=(d_h-90)/2;
$(document).ready(function(){
$("#document_height").css("margin-top",set_h);
});
</script>