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

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

/* change the font family and font size of body message */
div[class="ii gt adP adO"] {
  font-family: DejaVu Sans Mono, Liberation Mono, Luxi Mono, courier, arial, sans-serif !important;
  font-size: 8pt !important;
}

/* change the font family and font size of the textarea/div field */
textarea, div[class*="LW-avf"] {
  font-family: DejaVu Sans Mono, Liberation Mono, Luxi Mono, courier, arial !important;
  font-size: 8pt !important;
}

}