function expandNav() {

var x = document.getElementById("navbar");
var y = document.getElementById("navdrop");
var z = document.getElementById("navlist");
if (x.className === "site-nav") {
  x.className += " responsive";
} else {
  x.className = "site-nav";
}
if (y.className === "dropdown") {
  y.className += " responsive";
} else {
  y.className = "dropdown";
}
if (z.className === "dropdown-list") {
  z.className += " responsive";
} else {
  z.className = "dropdown-list";
}

}