This uses the simplemodal jQuery popup library. It will center the popup horizontally and place the top at 50px; It will also close the popup when clicking outside of the popup
* http://www.ericmmartin.com/projects/simplemodal/
<script type="text/javascript">
//close the popup when clicking outside of the popup
$.modal.defaults.overlayClose = true;
//center the popup horizontally and place at 50px from top vertically
$.modal.defaults.position = [50, ];
function showPopup()
{
$('#divPopup').modal();
}
</script>
<style>
#basic-modal-content {display:none;}
/* Overlay */
#simplemodal-overlay {background-color:#000;}
/* Container */
#simplemodal-container {height:360px; width:600px; color:#bbb; background-color:#333; border:4px solid #444; padding:12px;}
#simplemodal-container .simplemodal-data {padding:8px;}
#simplemodal-container code {background:#141414; border-left:3px solid #65B43D; color:#bbb; display:block; font-size:12px; margin-bottom:12px; padding:4px 6px 6px;}
#simplemodal-container a {color:#ddd;}
#simplemodal-container a.modalCloseImg {background:url(../img/basic/x.png) no-repeat; width:25px; height:29px; display:inline; z-index:3200; position:absolute; top:-15px; right:-16px; cursor:pointer;}
#simplemodal-container h3 {color:#84b8d9;}
</style>
<button onclick="showPopup();">Show Popup</button>
<div id="divPopup" style="display: none; ">
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</div>