.k {
	position: relative;
	-webkit-perspective: 300px;
	perspective: 300px;
}
.k span {
	display: block;
	position: absolute;
	width: 200px;
	height: 60px;
	border: 2px solid #333;
	text-align: center;
	line-height: 56px;
	-webkit-box-sizing: border-box;
	-moz-box-sizing: border-box;
	box-sizing: border-box;
	-webkit-transition: all .3s;
	transition: all .3s;
	
}
.k span:nth-child(1) {
	background-color: #333;
	color: #fff;
	-webkit-transform: rotateX(90deg);
	-moz-transform: rotateX(90deg);
	transform: rotateX(90deg);
	-webkit-transform-origin: 50% 50% -30px;
	-moz-transform-origin: 50% 50% -30px;
	transform-origin: 50% 50% -30px;
}
.k span:nth-child(2) {
	background-color: #fff;
	color: #333;
	-webkit-transform: rotateX(0deg);
	-moz-transform: rotateX(0deg);
	transform: rotateX(0deg);
	-webkit-transform-origin: 50% 50% -30px;
	-moz-transform-origin: 50% 50% -30px;
	transform-origin: 50% 50% -30px;
}
.k:hover span:nth-child(1) {
	-webkit-transform: rotateX(0deg);
	-moz-transform: rotateX(0deg);
	transform: rotateX(0deg);
}
.k:hover span:nth-child(2) {
	background-color: #333;
	-webkit-transform: rotateX(-90deg);
	-moz-transform: rotateX(-90deg);
	transform: rotateX(-90deg);
}