function setBlackLayerSize(){
	/*blackLayer = document.getElementById("blackDiv");
	blackLayer.style.height = window.innerHeight; 
	blackLayer.style.width = window.innerWidth;*/
}

function blackHide() {
	blackLayer = document.getElementById("blackDiv");
	blackLayer.style.visibility = "hidden";
}

function blackShow() {
  	setBlackLayerSize();
	blackLayer = document.getElementById("blackDiv");
  	blackLayer.style.visibility = "visible";
}