body{
	height:100%;
}
.container{

	position: relative;
	width: 300px;
	height: 300px;
	background-color: red;
	margin: auto;
	margin-top:-150px;
	top:50%;
}

.item{
	position: absolute;
	width: 100px;
	height: 100px;
	background-color: blue;
	left:0;
	right:0;
	top:0;
	bottom:0;
	margin: auto;
}