@namespace url(http://www.w3.org/1999/xhtml);

@-moz-document domain("mail.google.com") {

/* without labs */
div[class*="T0 pp aj3"] > div[class="ApVoH pY"] { display: none !important; }
/* with labs */
div[class*="T0 pp"] > div[class="ApVoH pY"] { display: none !important; }

}