animate.css/source/attention_seekers/heartBeat.css

@keyframes heartBeat{
  
  0%{
    transform: scale(1);
  }
  
  14%{
    transform: scale(1.3);
  }
  
  28%{
    transform: scale(1);
  }
  
  42%{
    transform: scale(1.3);
  }
  
  70%{
    transform: scale(1);
  }
  
}

.heartBeat{
  animation-name: heartBeat;
  animation-duration: 1.3s;
  animation-timing-function: ease-in-out;
}