HTML&CSS - width/height percentage

by Code_Garage

HTML

<div id="parent">
	<div id="child"></div>
</div>

CSS

#parent {
	width: 100px;
	height: 100px;
  background: #2980b9;
}

#child {
	width: 50%;
	height: 50%;
  background: #e74c3c;
}