为什么数值越大，边框越密集？ border-image:url(http://img1.sycdn.imooc.com//52e22a1c0001406e03040221.jpg) 20 repeat;
#border_image {
margin:0 auto;
height:100px;
line-height:100px;
text-align:center;
font-size:30px;
width:450px;
border:15px solid #ccc;
border-image:url(http://img1.sycdn.imooc.com//52e22a1c0001406e03040221.jpg) 20 repeat;
}
</style>
</head>
<body>
<div id="border_image">
请为我镶嵌上漂亮的画框吧
</div>
</body>
</html>
