.bt {
  background: #689b00;
  background-image: -webkit-linear-gradient(top, #99cc00, #669900);
  background-image: -moz-linear-gradient(top, #99cc00, #669900);
  background-image: -ms-linear-gradient(top, #99cc00, #669900);
  background-image: -o-linear-gradient(top, #99cc00, #669900);
  background-image: linear-gradient(to bottom, #99cc00, #669900);
  -webkit-border-radius: 28;
  -moz-border-radius: 28;
  border-radius: 28px;
  font-family: Arial;
  color: #ffffff;
  font-size: 20px;
  padding: 10px 20px 10px 20px;
  text-decoration: none;
}

.bt:hover {
  background: #689b00;
  background-image: -webkit-linear-gradient(top, #669900, #99cc00);
  background-image: -moz-linear-gradient(top, #669900, #99cc00);
  background-image: -ms-linear-gradient(top, #669900, #99cc00);
  background-image: -o-linear-gradient(top, #669900, #99cc00);
  background-image: linear-gradient(to bottom, #669900, #99cc00);
  text-decoration: none;
}