*{padding:0; margin:0;}

#wrapper {
	width:500px;
	margin-left:auto;
	margin-right:auto;
}

.block{height:100px; border:3px solid black}

#yellow{
	background-color:yellow;
	position:relative;
	right:70px;
	}
#red{
	background-color:red;
	}
#green{
	background-color:green;
	}
#blue{
	background-color:blue;
	position:relative;
	left:70px;
	}