@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

tab[label="(Untitled)"] {
margin-left: 5px !important;
margin-right: -295px !important;
padding-right: 300px !important;
}

tab[label="(Untitled)"] > hbox,
tab[label="(Untitled)"] > .tab-close-button {
  background-color: #FF9900 !important;
}

tab[label="(Untitled)"] .tab-text,
tab[label="(Untitled)"] > .tab-close-button,
tab[label="(Untitled)"] .tab-icon {
  display: none !important;
}