title: Bootstrap navbar does not work when minimising browsers
body: <p>I have a bootstrap navbar such as below. It works fine however when I minimise the window, the navbar becomes two times thicker than the navbar that appears on maximised window and the toggle do not show any menu. I appreciate any help. Thank you.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  &lt;head&gt;
  &lt;title&gt;&lt;/title&gt;
  
  &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" integrity="sha512-dTfge/zgoMYpP7QbHy4gWMEGsbsdZeCXz7irItjcC3sPUFtf0kuFbDz/ixG7ArTxmDjLXDmezHubeNikyKGVyQ==" crossorigin="anonymous"&gt;
  &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap-theme.min.css" integrity="sha384-aUGj/X2zp5rLCbBxumKTCw2Z50WgIr1vs/PFN4praOTvYXWlVyh2UtNUU0KAUhAX" crossorigin="anonymous"&gt;
  &lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js" integrity="sha512-K1qjQ+NcF2TYO/eI3M6v8EiNYZfA95pQumfvcVrTHtwQVDG+aHRqLi/ETn2uB+1JqwYqVG3LIvdm9lj6imS/pQ==" crossorigin="anonymous"&gt;&lt;/script&gt;
      &lt;meta name="viewport" content="width=device-width, initial-scale=1"&gt;
      &lt;/head&gt;
  
      &lt;body&gt;
      &lt;nav role="navigation" class="navbar navbar-inverse"&gt;
      &lt;!-- Brand and toggle get grouped for better mobile display --&gt;
      &lt;div class="navbar-header"&gt;
          &lt;a href="index.php" class="navbar-brand"&gt;Brand&lt;/a&gt;
      &lt;/div&gt;
      &lt;button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-ex1-collapse"&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;div id="navbarCollapse" class="collapse navbar-collapse"&gt;
          &lt;ul class="nav navbar-nav"&gt;
              &lt;li class="active"&gt;&lt;a href="index.php"&gt;Home&lt;/a&gt;&lt;/li&gt;
              &lt;li class="dropdown"&gt;
              &lt;a data-toggle="dropdown" class="dropdown-toggle" href="#"&gt;Categories&lt;b class="caret"&gt;&lt;/b&gt;&lt;/a&gt;
                  &lt;ul role="menu" class="dropdown-menu"&gt;
                      &lt;li&gt;&lt;a href="index1.php"&gt;Index 1&lt;/a&gt;&lt;/li&gt;
                      &lt;li class="divider"&gt;&lt;/li&gt;
                      &lt;li&gt;&lt;a href="index2.php"&gt;Index 2&lt;/a&gt;&lt;/li&gt;
                  &lt;/ul&gt;
              &lt;/li&gt;
          &lt;/ul&gt;
      &lt;form role="search" class="navbar-form navbar-right"&gt;
      &lt;div class="form-group"&gt;
      &lt;input type="text" placeholder="Search" class="form-control"&gt;
      &lt;/div&gt;
      &lt;/form&gt;
      &lt;ul class="nav navbar-nav navbar-right"&gt;
          &lt;li&gt;&lt;a href="#"&gt;Login&lt;/a&gt;&lt;/li&gt;
      &lt;/ul&gt;
      &lt;/div&gt;
      &lt;/nav&gt;
  </code></pre>