css-animation-iteration

HTML

<div class="heart"></div>

CSS

@keyframes heart {
    0% {
      transform: scale(5)
    }
    50% {
      transform: scale(1.1)
    }
    100% {
      transform: scale(1.2)
    }
  }
  
  .heart {
    height: 150px;
    width: 150px;
    background: url(https://2.bp.blogspot.com/-6_uL907PdR4/WaghYiFtJvI/AAAAAAAAAos/UmIzGWpbo1YcMghGQLjiBc8aA_rke5ypgCLcBGAs/s1600/heart.png) no-repeat 50%;
    animation: heart 1s 5;
  }