div {
    width:24px;
    height:24px;
    position:relative;
    -webkit-animation:glide 2s ease-in-out alternate infinite;
 }
 
 @-webkit-keyframes glide  {
    from {
       left:0px;
       top:0px;
    }
    
    to {
       left:0px;
       top:20px;
    }
 
 }



.center-img {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
  }


h1 {
	text-align: center;
    display: block;
    margin-left: auto;
    margin-right: auto;
	font-size: 35px;
	font-family: serif;
    color: red;
}