Untitled

<!DOCTYPE html>
<style>

body { margin: 0 }
.marg { margin: 100px }
.grow { animation: sca 2s }
@keyframes sca { 0% {transform: scale(0.5);} 100% {transform: scale(1);} }

.box {
  will-change: transform;
  display: inline-block;
  background: #9cd;
  width: 100px;
  height: 100px;
}

</style>
<div class="marg"><span class="grow"><div id="foo" class="box"></div></span></div>