.img{
	width: 256px;
	height: 225px;
	margin: 0 auto;
	background-size: 200px 200px;
	z-index: -1;
	position: relative;
}
.btn{
    width: 300px;
    height: 5px;
    position: absolute;
    left: 50%;
    bottom: 40px;
    margin-left: -80px;
    top: 750px;
}
.btn>span{
    display: block;
    width: 50px;
    height: 5px;
    float: left;
    background: #eee;
    margin-right: 5px;
    cursor: pointer;
}