Try this one :
<!DOCTYPE html>
<html>
<head>
<title>CSS animation timing function</title>
<style>
.box {
height: 150px;
width: 150px;
border-radius: 5px;
margin: 100px;
background-color:#4535AA;
animation: ghumo 4s linear 2 reverse forwards;
}
@keyframes ghumo {
0% { transform: rotate(0); background-color: #ED639E; }
100% { transform: rotate(360deg); background-color: #FFB643 }
}
</style>
</head>
<body>
<div class="box"></div>
</body>
</html>