Bootstrap navbar-toggler-icon not visible but functioning normally : <p>I am trying to get my bootstrap navbar implemented into my handlebars layout file. I've noticed some weird things happening with bootstrap and this is no exception. Once I shrink my window to a size where the navbar-toggler-icon should show, it is not visible, but it is still functioning there like it should, I just can't see it.</p>

<p>Here is my entire layout.hbs class:</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html lang="en"&gt;
  &lt;head&gt;
    &lt;!-- Required meta tags --&gt;
    &lt;meta charset="utf-8"&gt;
    &lt;meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"&gt;

    &lt;!-- Bootstrap CSS --&gt;
    &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous"&gt;
    &lt;link rel="stylesheet" href="/stylesheets/style.css"&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;nav id="navigation" class="navbar navbar-inverse"&gt;
      &lt;a class="navbar-brand" href="#"&gt;Navbar&lt;/a&gt;
      &lt;button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation"&gt;
        &lt;span class="navbar-toggler-icon"&gt;&lt;/span&gt;
      &lt;/button&gt;

      &lt;div class="collapse navbar-collapse" id="navbarSupportedContent"&gt;
        &lt;ul class="navbar-nav mr-auto"&gt;
          &lt;li class="nav-item active"&gt;
            &lt;a class="nav-link" href="#"&gt;Home &lt;span class="sr-only"&gt;(current)&lt;/span&gt;&lt;/a&gt;
          &lt;/li&gt;
        &lt;/div&gt;
    &lt;/nav&gt;
    {{{body}}}
    &lt;script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"&gt;&lt;/script&gt;
    &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"&gt;&lt;/script&gt;
    &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"&gt;&lt;/script&gt;
  &lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>Here is an example of whats happening:
<a href="https://i.stack.imgur.com/HZafG.png" rel="noreferrer">Picture of whats happening</a>
I was told changing my navbar class to <code>navbar-inverse</code> would make it appear but I had no luck with this either.</p>
