Techcrunch's Navbar Mobile Search Dropdown for Bootstrap

gistfile1.html

<nav class="navbar navbar-default" role="navigation">
      <div class="container-fluid">
        <div class="navbar-header">
          <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-2">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>
          <a class="navbar-brand" href="#">Brand</a>
        </div>
        <div class="navbar-collapse collapse in" id="bs-example-navbar-collapse-2" style="height: auto;">
          <form class="navbar-form" role="search">
    <div class="input-group">
          <input type="text" class="form-control">
          <div class="input-group-btn">
            <button type="button" class="btn btn-default" tabindex="-1"><i class="glyphicon glyphicon-search"></i></button>
            
            
          </div>
        </div>
</form>
        </div>
      </div>
    </nav>