Dear friend I use Jquery for popup : <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js" type="text/javascript"></script> <script> $(function() { var moveLeft = 0;var moveDown = 0;$('a.popper').hover(function(e) { var target = '#' + ($(this).attr('data-popbox')); $(target).show();moveLeft = $(this).outerWidth();moveDown = ($(target).outerHeight() / 2);}, function() {var target = '#' + ($(this).attr('data-popbox'));$(target).hide();}); $('a.popper').mousemove(function(e) {var target = '#' + ($(this).attr('data-popbox')); leftD = e.pageX + parseInt(moveLeft); maxRight = leftD + $(target).outerWidth(); windowLeft = $(window).width() - 40; windowRight = 0; maxLeft = e.pageX - (parseInt(moveLeft) + $(target).outerWidth() + 20); if(maxRight > windowLeft && maxLeft > windowRight) { leftD = maxLeft; } topD = e.pageY - parseInt(moveDown); maxBottom = parseInt(e.pageY + parseInt(moveDown) + 20); windowBottom = parseInt(parseInt($(document).scrollTop()) + parseInt($(window).height())); maxTop = topD; windowTop = parseInt($(document).scrollTop()); if(maxBottom > windowBottom) { topD = windowBottom - $(target).outerHeight() - 20; } else if(maxTop < windowTop){ topD = windowTop + 20; } $(target).css('top', topD).css('left', leftD); }); }); </script> CSS .popbox { display: none;position: absolute;z-index: 99999;width: 400px;padding: 10px;background: #EEEFEB;color: #000000;border: 1px solid #4D4F53;margin: 0px;-webkit-box-shadow: 0px 0px 5px 0px rgba(164, 164, 164, 1); box-shadow: 0px 0px 5px 0px rgba(164, 164, 164, 1); } .popbox h2 { background-color: #4D4F53; color: #E3E5DD; font-size: 14px; display: block; width: 100%; margin: -10px 0px 8px -10px; padding: 5px 10px; } How fix position in firefox.. Please help me. Thanks