IE z-index problem

I always test my website in both IE and FF for a fair compatibility. Then I ran into IE problem again.

Every z-index works fine in FF and I can’t click my buttons in IE.

I then figure out that the z-index is not working correctly in IE.

The cause is because IE needs the parent div of the nested div to have z-index too, then the nested div z-index will ‘active’.

Thanks again, IE.