function ckAddPreview() { // add a link, form & iframe // link submits form, posts to iframe target var formContainer = $("#main_content_inner"); var container = $('#vars

What is in your test_header.php file? If you use Firebug, are you able to see clearly the dimensions of where div#main is?

the main layout that comes with fuel minus the #main styles for the div in question which i had to comment out to show on this post):