var isInternetExplorer =(isInternetExplorer = navigator.appName.indexOf("Microsoft") != -1);
var yOffSet=(isInternetExplorer)? -91 : -4;

function setNeededHeight() {
			document.getElementById("main").style.visibility="hidden";
			document.getElementById("cont").style.visibility="visible";
			document.getElementById("main").style.height = document.getElementById("size").clientHeight - (document.getElementById("head").clientHeight+document.getElementById("foot").clientHeight);
			document.getElementById("cont").style.height = document.getElementById("size").clientHeight - (document.getElementById("head").clientHeight+document.getElementById("foot").clientHeight+yOffSet);
}