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

@-moz-document domain("mail.google.com") {
  div.yW, td.xY div.xS {
    color: #666 !important;
  }
  td.xY span.y2 {
    color: #aeaeae !important;
  }
  div.yW span.zF, td.xY b {
    color: #000 !important;
    font-weight: normal !important;
  }
}