function menu_n_toggle(item_id){
    var item = document.getElementById(item_id);

    var num_el = item.length - 1;
    var children = item.childNodes;

    for(var i = 0; i <= num_el; i++){
        var child = children[i];

        if(child.style.display == 'block'){
            child.style.display = 'none';
        }
        else{
            child.style.display = 'block';
        }
    }
}

function menu_n_set_position(item){
    var parent = item.parentNode;
    var parent_bottom = parent.offsetTop + parent.offsetHeight;

    item.style.top = parent_bottom + 'px';
}