@-webkit-keyframes pulse {
  0% {
  }
  50% {
    -webkit-transform: rotate(-180deg) scale(5);
            transform: rotate(-180deg) scale(5);
  }
  100% {
    -webkit-transform: rotate(-360deg) scale(0.2);
            transform: rotate(-360deg) scale(0.2);
  }
}

@keyframes pulse {
  0% {
  }
  50% {
    -webkit-transform: rotate(-180deg) scale(5);
            transform: rotate(-180deg) scale(5);
  }
  100% {
    -webkit-transform: rotate(-360deg) scale(0.2);
            transform: rotate(-360deg) scale(0.2);
  }
}

.pulse {
  -webkit-animation: pulse 4s alternate 2;
          animation: pulse 4s alternate 2;
  width: 300px;
  height: 100px;
  background: green;
  position: relative;
  margin: 200px auto 0;
  line-height: 100px;
  text-align: center;
  font-family: arial;
}