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

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

<nav>
  <ul> 
    <li><a></a></li>
    <li><a></a></li>
    <li><a></a></li>
    <li><a></a></li>
    </ul> 
  <dropdown> 
    <option><a></a></option> 
    <option><a></a></option>
    <option><a></a></option>
    <option><a></a></option>
  </dropdown>
</nav>

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; }
}