function find_largest_number(_arr_data)
{
	var i_biggest = 0;
	for(var i = 0; i < _arr_data.length; i++)
	{
		if (_arr_data[i] > i_biggest)
			i_biggest = _arr_data[i];
	}

	return i_biggest;
}

window.addEvent('domready', function()
{
	if ($('middlecontainer') && $('leftcontainer') && $('rightcontainer'))
	{
		//we make all our columns the same height as the longest one:
		var arr_data = Array(
					$('leftcontainer').getSize().y.toInt(),
					$('middlecontainer').getSize().y.toInt(),
					$('rightcontainer').getSize().y.toInt()
		);

		//we then set our left container the same height as the longest column - we do not forget to remove the padding of the leftcontainer from that number (30):
		$('leftcontainer').setStyle('height', find_largest_number(arr_data) - 30);
	}
});