.animation-box {
  width: 100%;
  height: 100px;
  border-radius: 4px;
  margin-bottom: 20px;
  background-color: #ff0000;
  animation: colorTransition 2s infinite alternate;
}

@keyframes colorTransition {
  0% {
  	background-color: #cccccc;
  }
  
  100%{
  	background-color: #eeeeee;
  }
}