.circle {

  background-color: white; 

  border: 1px solid red;

  border-radius: 50%;

  width: 50px;

  height: 50px;

  animation: pulse 1s infinte;

  -webkit-animation: pulse 1.2s infinite;

}

​

button {

  background-color: green; 

  border: none;

  border-radius: 50%;

  width: 50px;

  height: 50px;

}

​

​

​

@-webkit-keyframes pulse {

    from {

      width: 50px;

      height: 50px;

    }

    to {

      width: 100px

      height: 100px;

    }

}

​

@keyframes pulse {

    from {

      width: 50px;

      height: 50px;

    }

    to {

      width: 100px;

      height: 100px;

    }

}