jQuery - have popup box appear on screen regardless of how low they scroll

jQuery - have popup box appear on screen regardless of how low they scroll

I'm trying to create a popup box on a list of items that goes very much to
the bottom of the browser.
I want the POPUP to be in the center of the page where the user is at
regardless of how low they scrolled
i have to use POSITION ABSOLUTE not FIXED
but when i use POSITION ABSOLUTE the popup always appears on top and i
know its due to my top: 0
.lightbox-container{
border: solid red 1px;
width: 100px;
height: 40px;
background: yellow;
position: absolute;
top: 0;
}
I want to use something like scrollTop or one of those to get the popup to
always stay in the users viewpoint regardless of how low they scrolled
$('a').on('click', function(e){
var lightBox = $('<div class="lightbox-container"> <p>click to
remove</p>');
lightBox.appendTo('body');
$('.lightbox-container').on('click', function(e){
$(this).remove();
});
});
here is the fiddle im working on http://jsfiddle.net/2RNAN/1/
I know there are other posts about this but im very new to jquery and cant
seem to get it working.