function hidden_menu() {
    if (document.getElementById("top_menu_hidden")) {
        document.getElementById("top_menu_hidden").style.zIndex = "0";
    }
    /*document.getElementById("f1").style.display = "none";
    document.getElementById("f2").style.display = "none";
    */
}

function view_dropdown() {
    /*document.getElementById("f1").style.display = "block";
    document.getElementById("f2").style.display = "block";*/
    if (document.getElementById("top_menu_hidden")) {
        document.getElementById("top_menu_hidden").style.zIndex = "1001";
    }
}