<html>
<head>
<style>
#myDIV {
width: 300px;
height: 200px;
border: 1px solid black;
animation: mymove 5s infinite;
}
@keyframes mymove {
50% {border-bottom-width: 50px;}
}
</style>
</head>
<body>
<h1>Animation of border-bottom-width</h1>
<p>Gradually change the border-bottom-width property from 0 to 50px, then back:<p>
<div id="myDIV"></div>
<p><b>Note:</b> CSS Animations do not work in Internet Explorer 9 and earlier versions.</p>
</body>
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</html>