@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
 
tab {
   -moz-appearance: none !important; }
tab[selected="true"] {
   background-color: rgb(0,0,0) !important;
   color: red !important;
   font-style: italic !important; }

/* this code is for when the tab is hovered */
tab[selected="true"]:hover { 
   color: black !important;
   background-color: rgb(255,0,0) !important; }