If you look at my code pen my code pen and scroll down to the bottom of the page, and click a drop-down link the view jumps?
var nav = $('#menu > ul > li');
nav.find('li').hide();
nav.click(function () {
nav.not(this).find('li').hide();
$(this).find('li').slideToggle();
});
function openNav() {
document.getElementById("open").style.display = "none";
document.getElementById("close").style.display = "block";
$('#menu ul').slideToggle();
}
function closeNav() {
document.getElementById("open").style.display = "block";
document.getElementById("close").style.display = "none";
$('#menu ul').slideToggle();
}