Bootstrap Navbar in Drupal 8 - block--system-branding-block.html.twig

{% block content %}
  {% if site_logo %}
  <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">Toggle navigation</span>
      Menu
    </button>
    <a class="navbar-brand" href="{{ path('<front>') }}" title="{{ site_name }}" rel="home">
      <img src="{{ site_logo }}" alt="{{ site_name }}" />
    </a>
  </div>
  {% endif %}
{% endblock %}