@keyframes bnr-animation{
0% {width: 60px; background-color: #6cb371;}
50% {width: 234px; height: 60px; background-color: #ffd700;}
100% {width: 234px; height: 234px; background-color: #ff1493;}
}
.box {
width: 60px; height: 60px; background: #6cb371;
animation-name: bnr-animation;
animation-duration: 10s;
}
<div class="box"> </div>
