@-moz-document url-prefix(http://www.google.com/search), url-prefix(http://www.google.co.jp/search), url-prefix(http://www.google.co.jp/#) {
div#vsrs, .vsi, div#vsia, div#vsic, div#vsm, div#vspb, div#vspc, div#vspci, .vspib, .vspi {display: none !important;}
}

これでいけるはず