With CSS3 new features most of the browsers don't use the same properties they need to be prefixed with the browser specific property.

For example firefox is always prefixed with a -moz- and the chrome/sarafi is prefixed with a -webkit-.

Below is a snippet to be used for cross browser transparency for the opacity property.

selector {
	filter: alpha(opacity=50); /* internet explorer */
	-khtml-opacity: 0.5;      /* khtml, old safari */
	-moz-opacity: 0.5;       /* mozilla, netscape */
	opacity: 0.5;           /* fx, safari, opera */
}