// rollover actions for the navigation bar
// position subnav
function positionBelow (subnav, parentnav){
	yposition = parentnav.offsetHeight + 8;
	subnav.style.left = "0px";
	subnav.style.top =  yposition + "px";
}
// rollover action
function addRollover(subnav, parentnav) {
	positionBelow (subnav, parentnav);
	parentnav.onmouseover = function () { subnav.style.visibility = "visible"; }
	parentnav.onmouseout = function () { subnav.style.visibility = "hidden"; }
}
// all nav elements with sub navs need rollover actions
function initRollovers() {
	var topnav = document.getElementById("topnav");
	var subnavs = topnav.getElementsByTagName("ul");
	for (var i = 0; i < subnavs.length; i++) {
		var li = subnavs[i];
			addRollover(subnavs[i], subnavs[i].parentNode)
		}
}
// onload event
if (window.addEventListener)
	window.addEventListener("load", initRollovers, false);
else if (window.attachEvent)
	window.attachEvent ("onload", initRollovers);