border-radius结合transition的一个小应用（动画）

<br>    <meta charset="UTF-8"><br>    <title></title><br>    <style type="text/css"><br />        .box{<br />            display:block;<br />            height:350px;<br />            width:250px;<br />            background:#ddd;<br />            cursor:pointer;<br />            -webkit-transition: 0.4s;<br />            -moz-transition: 0.4s;<br />            -ms-transition: 0.4s;<br />            -o-transition: 0.4s;<br />            transition: 0.4s;<br />        }<br />        .box:hover{<br />            border-top-right-radius:180px 120px;background: rgba(246,246,247,0.9);<br />        }<br />    </style><br><br><br><a class="box"></a><br><br>