Center aligning windows opened with window.open in non IE browsers

[zspmhzx]

I'm opening an new page with window.open and I've found that I can only horizontally center it in IE with the following code. It will happily vertically center in Chrome, Firefox and Safari but that's it. Any thoughts on what could be causing this?\[code\]var left = Number((screen.width/2)-(700/2));var top = Number((screen.height/2)-(500/2));var windowFeatures = 'channelmode=0,directories=0,fullscreen=0,location=0,menubar=0,resizable=0,scrollbars=0,status=0,width=700,height=500,top='+top+'left='+left;window.open('access-modal.html', '', windowFeatures);\[/code\]