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

tabbrowser .tabbrowser-tabs tab[faviconized="true"] {
  min-width: 0 !important;
}

/* space between icon and text */
tab[faviconized="true"] .tab-middle {
  padding-right: 0 !important;
}

/* text margin */
tab[faviconized="true"] .tab-middle .tab-text {
  margin: 0 !important;
}