#tabbrowser-tabs:not([movingtab])
  > #tabbrowser-arrowscrollbox
  > .tabbrowser-tab
  > .tab-stack
  > .tab-background[multiselected]:not([selected]):-moz-lwtheme {
  background-image: linear-gradient(var(--toolbar-bgcolor, transparent), var(--toolbar-bgcolor, transparent)),
    linear-gradient(var(--toolbar-bgcolor), var(--toolbar-bgcolor)), var(--lwt-header-image, none) !important;
}

.tab-background[multiselected="true"]:not([selected="true"]) > .tab-loading-burst:not([bursting]) {
  background: color-mix(in srgb, currentColor 65%, transparent);
  opacity: 0.3;
}
#TabsToolbar[brighttext]
  .tab-background[multiselected="true"]:not([selected="true"])
  > .tab-loading-burst:not([bursting]) {
  opacity: 0.15;
}


@include Option("userChrome.tab.connect_to_window") {
  .tab-background[multiselected=true] {
    outline: none !important;
  }
}
@include NotOption("userChrome.tab.connect_to_window") {
  /* Backport from FF 99 */
  .tab-background[multiselected=true] {
    outline: 1px solid color-mix(in srgb, var(--focus-outline-color, currentColor) 40%, transparent);
    outline-offset: -1px;
  }

  .tab-background[multiselected=true][selected=true] {
    outline-width: 2px;
    outline-offset: -2px;
  }
}