centering with absolute position

dabblet.css

/**
 * centering with absolute position
 */
div.header {	
	width: 100%;	
	background-color:green;	
	height: 30px;	
	position:relative;
}
div.container {
	position:relative;
	width: 100%;
	height: 400px;
}

div.body {
	width: 100px;
	height: 100px;
	background-color: red;

	position: absolute;
	top:0;
	bottom: 0;
	left: 0;
	right: 0;
	
	margin: auto;
}
div.footer {
	width: 100%;
	background-color:yellow;
	height: 30px;
	position:relative;
}

div.impressum {	
	width: 20px;	
	background-color:blue;	
	height: 30px;	
	position:relative;
	margin-left: 10%;
}

dabblet.html

<div class="header"></div><div class="container"><div class="body"></div></div><div class="footer"><div class="impressum"></div></div>

settings.json

{"view":"split-vertical","fontsize":"100","seethrough":"","prefixfree":"1","page":"result"}