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

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

/* --- logo --- */
body[onload="Print()"] > div > table:first-child img[src*="/images/logo"],
/* --- email address (top right) --- */
body[onload="Print()"] > div > table:first-child b
  {
    display: none !important;
  }
}