.img-box{
	padding-bottom:100%;
}
.img-box img{
	position:absolute;
	top:0;
	bottom:0;
	left:0;
	right:0;
	width:100%;
	margin:auto;
}


/*.box{
	width: 50%;
	margin: 50px auto;
}
.img-box{
	width: 100%;
	position:relative;
	z-index:1;
}
.img-box img{
	position:absolute;
	top:0;
	bottom:0;
	left:0;
	right:0;
	width:100%;
	margin:auto;
	z-index: -1;
	*zoom:1;
}
.img-box:before {
	content: "";
	display: inline-block;
	padding-bottom: 100%;
	width: 0.1px;
	vertical-align: middle;
}
*/
/*--------------------- 
作者：zh_rey 
来源：CSDN 
原文：https://blog.csdn.net/zh_rey/article/details/69666232 
版权声明：本文为博主原创文章，转载请附上博文链接！
*/