.demo {

    width: 300px;

    height: 140px;

    border: 1px solid #999;

    background: rgba(100,100,100,0.5) url(http://static.mukewang.com/static/img/logo_index.png) left top no-repeat , 

               url(http://static.mukewang.com/static/img/logo_index.png) right bottom no-repeat;

}