.online{ display:inline-block; width:1.43rem; height:2.02rem; background:url(https://img10.360buyimg.com/ddimg/jfs/t1/78637/16/20047/20815/62a9cce7Ec6b6af53/c3c387145cabfec6.png) no-repeat center center; background-size:1.43rem 2.02rem; position:fixed; top:50%; right:0; margin-top: -3.2rem; z-index:99}