offsetTop
element.offsetTop does different things in gecko than IE, best bet is to use the function listed here: http://www.quirksmode.org/js/findpos.html, the code:
function findPos(obj) {
var curleft = curtop = 0;
if (obj.offsetParent) {
curleft = obj.offsetLeft
curtop = obj.offsetTop
while (obj = obj.offsetParent) {
curleft += obj.offsetLeft
curtop += obj.offsetTop
}
}
return [curleft,curtop];
}