UL#messages LI {
  background-repeat: no-repeat;
  background-position: 5px 4px;
  padding-left: 1.5em;
}
UL#messages LI.success {
  background-image: url('images/success.gif');
  background-color: lime;
}
UL#messages LI.warning {
  background-image: url('images/warning.gif');
  background-color: orange;
}
UL#messages LI.error {
  background-image: url('images/warning.gif');
  background-color: red;
}