td.yes {
  font-weight: bold;
  text-align: center;
 /* background-color: #ffff44; */
  background-color: #00ff00;
}

td.no {
  text-align: center;  
  background-color: #ffe0e0;
}

td.unknown {
  text-align: center;
  color: #ff0000;
}