Fixed missing component in responsive navbar. No longer becomes unusable on small screens

app/views/application/_header.html.erb

@@ -5,6 +5,12 @@ Content changes if the user is logged in or admin
 <header id="header">
   <nav class="navbar navbar-default">
     <div class="navbar-header">
+      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
+        <span class="sr-only"><%=t('nav') %></span>
+        <span class="icon-bar"></span>
+        <span class="icon-bar"></span>
+        <span class="icon-bar"></span>
+      </button>
       <a class="navbar-brand" href="/"><%=t('.app_title') %></a>
     </div>
     <div id="navbar" class="navbar-collapse collapse">

config/locales/en.yml

@@ -11,6 +11,7 @@
 # available at http://guides.rubyonrails.org/i18n.html.
 
 en:
+  nav: "Navigation Menu"
   something_wrong: "Sorry, something went wrong"
   email_request_flash: "Supply an email address for response"
   in_touch: "We'll be in touch"