Quick css snippet for a 100% viewport width and height for full screen background images and the like. Keeps everything in the flow of the DOM as well.

100% viewport height and width

/* Parent Element */  
#background-container {
	height: 100%;
	min-height: 100%;
	width: 100%;
  	position: relative;
	background: black;
}

/* Child Element */
#background {
	width: 100%;
	height: 100%;
  	position: absolute;
	bottom: 0;
	background: red;
}