@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

@-moz-document url(chrome://browser/content/browser.xul) {
  tab {
    padding: 0 !important;
    margin: 2px !important;
  }

  tab > .tab-middle{
    padding: 1px 4px 2px !important;
  }

  tab:not([selected="true"]) {
    -moz-appearance: button !important;
  }

  tab:not([selected="true"]) > .tab-middle {
    /* you can change the background color of active tab here */
  }

  tab[selected="true"] {
    -moz-appearance: textfield !important;
    margin-left: 0 !important;
    padding-left: 1px !important;
  }

  tab[selected="true"] > .tab-middle {
    background-color: #efeee9;
  }

  tab:focus > .tab-middle {
    outline: none !important;
  }
}