CSS Popup Position (top & left not working)
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I've followed the tutorial below to get a popup working:
http://www.pat-burt.com/web-development/how-to-do-a-css-popup-without-opening-a-new-window/

I have one caveat though.  Sometimes the pages it will be popping up from are really, really long.  The code in the tutorial has it popping up in the center.  Vertically, this is not acceptable. I'm trying to get it to pop up in the center, but at the very top.  I've used top: 0px; and for testing purposes left: 0px; (and a few others) but it seems to matter not.  Always pops up in the center.

You can take a look at the latest one I've done here:
https://www.gamengai.com/popup.php#

Am I missing something?