message: wrap hamburger menu contents + trigger for easier external control of visibility
diff: +<div ...attributes>
  <button
  type="button"
  class="hamburger-menu__trigger"
  disabled={{@open}}
  {{on "click" (optional @onOpen)}}
  - ...attributes
  >
  {{svg-jar "hamburger-menu" width="20" height="14"}}
  </button>
  </ul>
  </nav>
  {{/if}}
  +</div>
  \ No newline at end of file
  