Toggle

    function navhide() {
     var navtoggle = 1;
     if (navtoggle == 1) {
        var navtoggle = 2;
        document.getElementById('nav-hide').style.visibility = 'visible';
     } else {
        var navtoggle = 1;
        document.getElementById('nav-hide').style.visibility = 'hidden';
     }
    }