I have made a Fiddle for reference: http://jsfiddle.net/xypQY/
Which element would i apply WebKit transitions on to achieve a Fade In effect using opacity?
This is a webkit bug, transitions do not work in Chrome or Safari on pseudo-elements.
Please star this bug to hopefully help the ball get rolling on a fix:
It has been reported to Webkit:
so hopefully it will be fixed soon.
UPDATE: Support for transitions was added to Webkit on 01/02/2013: https://trac.webkit.org/changeset/138632