#col_one 
{
	position: relative;
	float: left; 
	width:50%; 
	padding-bottom: 1001em;     /* X + padding-bottom */
	margin-bottom: -1000em;     /* X */
}

#col_two{
	position: relative;
	float: left;
	padding-bottom: 1001em;     /* X + padding-bottom */
	margin-bottom: -1000em;     /* X */
}