@-moz-document url-prefix(http://mail.google.com/),url-prefix(https://mail.google.com/)
{

.mb, .tb {font-family: MonoSpace !important; font-size: 9pt !important; }
.mb * { font-size: 10pt !important; }
  div[id] > div[class][style] > div[class] > div[id][class],
  textarea[spellcheck="true"] 
  {
     font-family: monospace !important; 
     font-size: 13px !important; 
  }
}