Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<head>
<style> 
#myDIV {
    width: 300px;
    height: 200px;
    border: 1px solid black;
    -webkit-animation: mymove 5s infinite; /* Chrome, Safari, Opera */
    animation: mymove 5s infinite;
}

/* Chrome, Safari, Opera */
@-webkit-keyframes mymove {
    50% {border-top-width: 15px;}
}

/* Standard syntax */
@keyframes mymove {
    50% {border-top-width: 15px;}
}
</style>
</head>
<body>

<p>Gradually change the border-top-width property from 1px to 15px then back:<p>
<div id="myDIV"></div>

<p>The border-top-width is <em>animatable</em> in CSS.</p>
<p><b>Note:</b> CSS Animations do not work in Internet Explorer 9 and earlier versions.</p>

</body>
</html>