tabsOnBottom.css

/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/tabs_on_bottom_v2.css made available under Mozilla Public License v. 2.0
See the above repository for updates as well as full license text. */

/* This reorders toolbar to place tabs below other toolbars. Requires Firefox 133+ */

@media (-moz-bool-pref: "userchrome.force-window-controls-on-left.enabled"){
  #nav-bar > .titlebar-buttonbox-container{
    order: -1 !important;
    > .titlebar-buttonbox{
      flex-direction: row-reverse;
    }
  }
}
@media not (-moz-bool-pref: "sidebar.verticalTabs"){
  .global-notificationbox,
  #tab-notification-deck,
  #TabsToolbar{
    order: 1;
  }
  #TabsToolbar > :is(.titlebar-spacer,.titlebar-buttonbox-container){
    display: none;
  }
  :root[sizemode="fullscreen"] #nav-bar > .titlebar-buttonbox-container{
    display: flex !important;
  }
  :root[tabsintitlebar] #toolbar-menubar:not([autohide="false"]) ~ #nav-bar{
    > .titlebar-buttonbox-container{
      display: flex !important;
    }
    :root[sizemode="normal"] & {
      > .titlebar-spacer{
        display: flex !important;
      }
    }
    :root[sizemode="maximized"] & {
      > .titlebar-spacer[type="post-tabs"]{
        display: flex !important;
      }
      @media (-moz-bool-pref: "userchrome.force-window-controls-on-left.enabled"),
        (-moz-gtk-csd-reversed-placement),
        (-moz-platform: macos){
        > .titlebar-spacer[type="post-tabs"]{
          display: none !important;
        }
        > .titlebar-spacer[type="pre-tabs"]{
          display: flex !important;
        }
      }
    }
  }
}