function showHide(ID){
	if (document.getElementById) {
		if (document.getElementById(ID).style.display !== "block"){
			document.getElementById(ID).style.display = "block";
		}else{
			document.getElementById(ID).style.display = "none";
		}
	}
}
function show(ID){

	document.getElementById(ID).style.display = "block";

}
function hide(ID){

	document.getElementById(ID).style.display = "none";

}
function showNav(){

	show('mainMenu');
	hide('navArrows');

}