purpose: Navigation with a dropdown and a listener for selection.

code: |
  <Nav id="mainNav" vertical></Nav>
  <script>
  const nav = document.querySelector('#mainNav')
  nav.state.list = [
    { type: 'button', name: 'home', label: 'Home', icon: 'house' },
    { type: 'dropdown', name: 'admin', label: 'Admin', items: [
      { type: 'button', name: 'users', label: 'Users' },
      { type: 'button', name: 'roles', label: 'Roles' }
    ] }
  ]
  nav.addEventListener('change', event => openPage(event.detail))
  </script>