<div class='target'></div>

$unit: 1em;

.target {
	width: 18*$unit; height: 18*$unit;
	background: radial-gradient(
		#000 $unit, transparent 0, 
		transparent 3*$unit, #000 0, 
		#000 5*$unit, transparent 0, 
		transparent 7*$unit, #000 0, 
		#000 9*$unit, transparent 0
	);
}