firefox != IE

https://developer.mozilla.org/en/Understanding_CSS_z-index/Stacking_context_example_1

try the HTML code below and as usual, it will not show the same way in IE and firefox, this is probably my biggest problem right now, i'll just use the HTML code in the link to describe my problem. the goal is to make div2 appear above div3 (again in IE - because this works fine in firefox).

the constraints are only the css part can be edited and the z-index of div3 cannot be -1