CSS实现横线两段逐渐变细变淡

图片说明

请问大家，怎么用CSS实现上图中横线两端逐渐变细变淡的效果？

用css3渐变就好啦！

 <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box{
            width:500px;
            height:2px;
            background: -webkit-linear-gradient(left, #fff 14%,#333 50%,#fff 100%);
        }
    </style>
</head>
<body>
<div class="box"></div>
</body>
</html>

http://www.cnblogs.com/ritazhang/p/6109544.html