title: drop down menu bootsrap 3 wont work
body: <p>I want to create a navbar with a drop down menu for mobile phones.
  I've did this for some other websites and it always worked fine.</p>
  
  <p>Now all of a sudden it stopped working and I wonder why..</p>
  
  <p>This is the code:</p>
  
  <pre><code>&lt;head&gt;
      &lt;title&gt;TODO supply a title&lt;/title&gt;
      &lt;meta charset="UTF-8"&gt;
      &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt;
      &lt;!-- Latest compiled and minified CSS --&gt;
      &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" integrity="sha384-1q8mTJOASx8j1Au+a5WDVnPi2lkFfwwEAa8hDDdjZlpLegxhjVME1fgjWPGmkzs7" crossorigin="anonymous"&gt;
  
      &lt;!-- Optional theme --&gt;
      &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap-theme.min.css" integrity="sha384-fLW2N01lMqjakBkx3l/M9EahuwpSfeNvV63J5ezn3uZzapT0u7EYsXMjQV+0En5r" crossorigin="anonymous"&gt;
  &lt;/head&gt;
  
  
  &lt;body&gt;
      &lt;nav class="navbar navbar-inverse navbar-fixed-top" id="my-navbar"&gt;
          &lt;div class="container"&gt;
              &lt;div class="navbar-header"&gt;
                  &lt;button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbar-collapse"&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 href="" class="navbar-brand"&gt;Marco Koopman&lt;/a&gt;
  
              &lt;/div&gt;
              &lt;div class="collapse navbar-collapse" id="navbar-collapse"&gt;
                  &lt;ul class="nav navbar-nav"&gt;
                      &lt;li&gt;&lt;a href=""&gt;About me&lt;/a&gt;&lt;/li&gt;
                      &lt;li&gt;&lt;a href=""&gt;My school&lt;/a&gt;&lt;/li&gt;
                      &lt;li&gt;&lt;a href=""&gt;My skills&lt;/a&gt;&lt;/li&gt;
                      &lt;li&gt;&lt;a href=""&gt;More info&lt;/a&gt;&lt;/li&gt;
                  &lt;/ul&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/nav&gt;
  
  
       &lt;!-- Latest compiled and minified JavaScript --&gt;
      &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js" integrity="sha384-0mSbJDEHialfmuBBQP6A4Qrprq5OVfW37PRR3j5ELqxss1yVqOtnepnHVP9aJ7xS" crossorigin="anonymous"&gt;&lt;/script&gt;
      &lt;script src="https://code.jquery.com/jquery-2.2.4.min.js"/&gt;
  
  &lt;/body&gt;
  </code></pre>