@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
@-moz-document url(chrome://browser/content/browser.xul) {

#urlbar-progress-alt{
height: 24px !important;
margin: -1px 0px -1px -1px !important;
background: transparent !important;
}

#urlbar-progress-alt .progress-bar
{
   -moz-appearance: progresschunk !important;
   background-color: transparent !important;
   opacity: .5 !important;
}

#urlbar-progress-alt .progress-bar,
#urlbar-progress-alt .progress-remainder {
 border: 0 !important;
}
}