#btn {
        width: 60px;
        height: 40px;
        position: fixed;
        display: none;
        right: 0px;
        bottom: 30px;
        background: url(/images/top.jpg) no-repeat left top;
    }
             
#btn:hover {
        background: url(/images/top.jpg) no-repeat 0 -40px;
    }
             
    .box {
        width: 1190px;
		height: 600px;
        margin: 0 auto;
    }