<html>
<head>
<style>
#myDIV {
background-color:lightblue;
width: 100%;
block-size: 30px;
animation: mymove 5s infinite;
}
@keyframes mymove {
50% {block-size: 100px;}
}
</style>
</head>
<body>
<h1>Animation of block-size</h1>
<p>Gradually change the block-size property from 30px to 100px, and back to 30px:<p>
<div id="myDIV">
This is my DIV element.
</div>
</body>
</html>