#box{
	position: absolute;
}

#box div{
	width: 740px;
/* 	height: 50px; */
	height: 5em;
	float: left;
	background: #fff;
}

.mask{
	position: relative;
	width: 740px;
	/*   height: 50px; */
	height: 5em;
	overflow: hidden;
}