.slider-outer{
		width:100%;
		height:700px;
		position: relative;
		overflow:hidden;
	}
.slider-outer .img-item{
		position: absolute;
		width:20%;
		height: 100%;
		transition: all 1s;
		/*设置子元素在3D空间中呈现*/
		transform-style: preserve-3d;
	}
	/*让图片可以构成一个有四个面的长方体 start*/
.slider-outer .img-item .img{
		width: 100%;
		height: 100%;
		position: absolute;
		background-size: cover;
	}
.slider-outer .img-item .img:nth-child(1){
		background: url(../images/banner1.jpg) no-repeat;
		transform: rotateX(0deg) translateZ(150px);
	}
.slider-outer .img-item .img:nth-child(2){
		background: url(../images/banner2.jpg) no-repeat;
		transform: rotateX(90deg) translateZ(150px);
	}
.slider-outer .img-item .img:nth-child(3){
		background: url(../images/banner4.jpg) no-repeat;
		transform: rotateX(180deg) translateZ(150px);
	}
.slider-outer .img-item .img:nth-child(4){
		background: url(../images/banner1.jpg) no-repeat;
		transform: rotateX(270deg) translateZ(150px);
	}
	/*让图片可以构成一个有四个面的长方体 end*/
.slider-outer .btns{
		position: absolute;
		top: 50%;
		width: 100%;
		height: 70px;
		margin-top: -35px;
	}
.slider-outer .btns .prev, .slider-outer .btns  .next{
		width: 70px;
		height: 70px;
		line-height: 70px;
		text-align: center;
		background-color: rgba(0,0,0,.3);
		color: #fff;
		font-size: 30px;
		cursor: pointer;
		position: absolute;
	}
.slider-outer .btns .prev{
		left: 0;
	}
.slider-outer .btns .next{
		right: 0;
	}