* {
	margin:0;
	padding:0;
}
.contain {
	width:580px;
	height:370px;
	margin:50px auto;
	border:1px solid #ccc;
}
.contain ul li {
	float:left;
	width:180px;
	height:110px;
	list-style:none;
	margin:10px 0 0 10px;
}
.contain .item {
	width:180px;
	height:110px;
	background:#ccc;
}
.contain img {
	width:180px;
	height:110px;
	border-radius:5px;
	cursor:pointer;
}
通过拖拽效果实现图片的位置切换,后面的拖拽到前面