Bootstrap toggable menu icon doesn't work on small device
<p>i added at my hoe page a navbar with toggable icon on small screen; It is the typical navbar of bootstrap.
I have the problem that when i go on developer tool and resize the screen in order to test the responsive part, happen that the icon doesn't toggle, it is like is not active.</p>

<p>Any help?</p>

<p>Here is the code:</p>

<pre><code>&lt;nav id="header" class="navbar navbar-default"&gt;
      &lt;div class="container"&gt;
        &lt;!-- Brand and toggle get grouped for better mobile display --&gt;
        &lt;div class="navbar-header"&gt;
          &lt;button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navmenu" aria-expanded="false" aria-controls="navmenu"&gt;
            &lt;span class="sr-only"&gt;Toggle navigation&lt;/span&gt;
            &lt;span class="icon-bar"&gt;&lt;/span&gt;
            &lt;span class="icon-bar"&gt;&lt;/span&gt;
            &lt;span class="icon-bar"&gt;&lt;/span&gt;
          &lt;/button&gt;
          &lt;a class="navbar-brand" href="#"&gt;&lt;img id="logo" src="images/art-of-hair.png"&gt;&lt;/a&gt;
        &lt;/div&gt;

        &lt;!-- Collect the nav links, forms, and other content for toggling --&gt;
        &lt;div id="navmenu" class="collapse navbar-collapse navbar-right"&gt;
          &lt;ul class="nav navbar-nav"&gt;
            &lt;li class="active"&gt;&lt;a href="#"&gt;Home&lt;span class="sr-only"&gt;Home&lt;/span&gt;&lt;/a&gt;&lt;/li&gt;
            &lt;li&gt;&lt;a href="#"&gt;Hair Styles&lt;/a&gt;&lt;/li&gt;
            &lt;li class=""&gt;&lt;a href="#" class=""&gt;About&lt;/a&gt;&lt;/li&gt;
            &lt;li class=""&gt;&lt;a href="#" class=""&gt;Contact&lt;/a&gt;&lt;/li&gt;
          &lt;/ul&gt;


        &lt;/div&gt;&lt;!-- /.navbar-collapse --&gt;
      &lt;/div&gt;&lt;!-- /.container-fluid --&gt;
    &lt;/nav&gt;
</code></pre>

<p>and css:</p>

<pre><code> * {
    margin: 0;
}

body {
    font-family: 'Alice', serif;
}

#header {
    height:200px;

}

#logo {
    width: 300px;
    height:150px;
}

#navmenu {
    margin:30px 120px 0 0;
}
</code></pre>