function show_nav(id){
var obj = document.getElementById(id);
if (obj.style.display == "block"){
obj.style.display = "none";
return false;
}
close_nav();
obj.style.display = "block"; 
return false;
}
function close_nav(){
var obj = document.getElementById('navigation-container');
for (var i in obj.childNodes) {
var li = obj.childNodes[i];
if (li.nodeName == "LI"){
    for (var i in li.childNodes){
        if (li.childNodes[i].nodeName == 'UL'){
            li.childNodes[i].style.display = 'none';
        }
    }
}
}
}