userChrome.css

#titlebar {
  -moz-box-ordinal-group: 2;
}

#TabsToolbar .toolbar-items {
  background: linear-gradient(rgb(215,215,215), rgb(205,205,205));
}

#PlacesToolbar .toolbarbutton-icon {
  visibility: collapse;
}

#PlacesToolbar toolbarbutton.bookmark-item {
  padding: 0 6px !important;;
}

.tab-line {
  display: none;
}

.tab-background[selected="true"] {
  border-top-style: none !important;
}

.tab-content {
    padding: 0 8px;
}

.tab-close-button {
  -moz-box-ordinal-group: 0;
  margin-inline-end: 5px !important;
}

.toolbarbutton-icon {
  filter: grayscale(1.0);
}

.tabbrowser-tab::after, .tabbrowser-tab::before {
  opacity: 0.2 !important;
}

/* #personal-bookmarks { */
/*   -moz-box-flex: inherit; */
/* } */

#PlacesToolbarItems {
  -moz-box-pack: center;
}

toolbarbutton#appMenu-logins-button {
  display: none;
}

menu#fill-login, menu#fill-login + menuseparator {
  display: none;
}

/* toolbox#navigator-toolbox { */
/*   border-bottom: 0.5px rgba(0,0,0,0.2) solid !important; */
/*   box-shadow: 0 0 5px 0px rgba(0,0,0,0.2); */
/* } */