图片居中显示

gistfile1.html

<ul class='thumbnails'>
    <li>
        <a class='thumbnail'>
            <img src='http://ww1.sinaimg.cn/mw690/a1d3feabjw1e57a6ito1gj205a02sq37.jpg' />            
        </a>
    </li>
</ul>

gistfile2.css

.thumbnail {
    display:block;
    padding:4px;
    overflow:hidden;
}

.thumbnail{
    width:100px;
    height:100px;
    overflow:hidden;
    padding:4px;
    display:table-cell;
    vertical-align:middle;
}