#pasbut
{
  display: block;
  width: 130px;
  height: 25px;
  background: url("http://scottcoletti.com/fx/pasbut1.gif") no-repeat 0 0;

}
pasbut:hover
{ 
  background-position: 0 -35px;
}

#pasbut span
{
  display: none;
}