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

@-moz-document url("chrome://browser/content/browser.xul") {

#bookmarksBarContent > toolbarbutton > menupopup > menuseparator:last-of-type {display: none !important;}
menuitem[oncommand="openUILink(this.getAttribute('siteURI'), event);"],
menuitem[oncommand="PlacesUIUtils.openContainerNodeInTabs(this.parentNode._resultNode, event);"],
menuseparator[builder="end"] {

   display:none   !important;

}

}