Convert a Menu to a Dropdown for Small Screens

Two menus, one for large screen, another for small screen

One menu is a set of buttons, another is a dropdown list

Choose one of them to display based on screen size

---

nav dropdown {
  display: none;
}
@media (max-width: 960px) {
  nav ul          { display: none; }
  nav dropdown    { display: inline-block; }
}