I do not believe (and i could be wrong) that it is possible to have a transparent input with non-transparent text.
The fix for this problem with div.elements was to layer divs, but that is not possible with the input of a text box. You could likely getting a very complex javascript/layer solution to work, but the example at
Planet Renders v3 simply uses background images and a hover state... no transparency.
This help at all?
Mike.