HTML
CSS
JavaScript
HTML
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"> 
<title>笔下光年</title>
</head>
<body>

<p>逐步改变 outline-width 属性，从 5px 到 50px：<p>
<div id="myDIV"></div>

<p>outline-width 属性支持动画效果。</p>
<p><b>注意：</b>Internet Explorer 9 及更早 IE 版本不支持 CSS 动画。</p>

</body>
</html>
CSS
#myDIV {
    margin: auto;
    border: 1px solid black;
    outline: coral solid 5px;
    width: 300px;
    height: 300px;
    -webkit-animation: mymove 5s infinite; /* Chrome, Safari, Opera */
    animation: mymove 5s infinite;
}

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

/* Standard syntax */
@keyframes mymove {
    50% {outline-width: 50px;}
}
JavaScript