userChrome.css for firefox wth tree style tabs

userChrome.css

#main-window[tabsintitlebar="true"]:not([extradragspace="true"]) #TabsToolbar
> .toolbar-items {
  opacity: 0;
  pointer-events: none;
}
#main-window:not([tabsintitlebar="true"]) #TabsToolbar {
  visibility: collapse !important;
}
#sidebar-header {
  display: none;
}