br{
	clear:both;
	line-height:0;
}

#container{
	margin: 10px auto;
	border:1px solid #000;
	background:#9cf;
	width:50%;
}

#container div{
	background:#fff;
	border:1px dashed #000;
	padding:10px;
	margin:10px;
}

#left-column{
	width:100px;
	float:left;
}
#left-column + #centre-column{
	margin-left:140px;
}

#right-column{
	width:100px;
	float:right;
}
#right-column + #centre-column,
#right-column + #left-column + #centre-column{
	margin-right:140px;
}