fixup! BB 32308: Use direct browser sizing for letterboxing.

    outline-width: var(--letterboxing-outline-width);

  }

  #tabbrowser-tabpanels {

    /* Override the --tabpanel-background-color.

     * Also, make sure this remains transparent, otherwise it will overlap the

     * parent's corner's border-radius due to it's "position: relative" rule. */

  /* Override the --tabpanel-background-color. */

  /* TODO: FIX this for newtab pages. tor-browser#44085 */

    background: transparent;

  }

  --tabpanel-background-color: transparent;

  /* stylelint-disable-next-line media-query-no-invalid */

  @media -moz-pref("sidebar.revamp") {