Weblog responsive navigation (paste into your code injection pane)

responsive-navigation-snippet.html

<style>
  .menu-toggle {
    display: block;
  }

  header nav.hidden {
    display: none;
  }

  @media all and (min-width: 800px) {
    header nav.hidden {
      display: block;
    }
    .menu-toggle {
      display: none;
    }
  }
</style>

<script>
  window.onload = function(){
    document.querySelector("header .main-header__text-container").insertAdjacentHTML( 'afterend', '<a class="menu-toggle" onclick="toggleMenu();" href="#!"><b>≡ MENU</b></a>' );
    document.querySelector(".menu-toggle").hidden = false;
    document.querySelector("header nav").classList.add("js");
    toggleMenu = function(){
      document.querySelector("header nav").classList.toggle("hidden");
    }
    toggleMenu()
  };
</script>