//	Grab the list items in the main navigation list and run hide or show functions as appropriate.
function drop_down() 
{
	//	Make sure browser is capable to doing the things we need.
	if(!document.getElementsByTagName) return false;
	if(!document.getElementById) return false;
	
	//	Do the class changes as appropriate.
	var list_items = document.getElementById("main_navigation").getElementsByTagName("li");
	var i = 0;
	while (i < list_items.length) 
	{
		list_items[i].onmouseover=function() 
		{
			this.className+=" drop_down";
		}
		list_items[i].onmouseout=function() 
		{
			this.className=this.className.replace(new RegExp(" drop_down\\b"), ""); 
		}
		
		i++;
	}
}

window.onload = drop_down;