startList = function() {
	var navRoot = document.getElementById('drop-down-nav');	
	var theLIs = navRoot.getElementsByTagName('li');
	for(var x =0; x < theLIs.length; x++) {
		var hasChildULs = theLIs[x].getElementsByTagName('ul');
		if (hasChildULs.length > 0) { 
			theLIs[x].onmouseover = function() { 
				this.className += ' over';
				this.style.zIndex = '1';
			}
			theLIs[x].onmouseout = function() { 
				this.className = '';
			}
		}
	}
}

window.onload = startList;