Flat UI Panel

HTML

<link rel="stylesheet" href="http://designmodo.github.io/Flat-UI/dist/css/vendor/bootstrap.min.css">
<link rel="stylesheet" href="http://designmodo.github.io/Flat-UI/dist/css/flat-ui.css">
<script src="http://designmodo.github.io/Flat-UI/dist/js/vendor/jquery.min.js"></script>
<script src="http://designmodo.github.io/Flat-UI/dist/js/flat-ui.min.js"></script>
<script src="http://designmodo.github.io/Flat-UI/docs/assets/js/application.js"></script>
<form class="navbar-form navbar-right" action="#" role="search">
  <div class="form-group">
    <div class="input-group">
      <input class="form-control" id="navbarInput-01" type="search" placeholder="Search">
      <span class="input-group-btn">
        <button type="submit" class="btn"><span class="fui-search"></span></button>
      </span>
    </div>
  </div>
</form>

CSS

body {
    padding: 40px;
}

.open > .dropdown-menu {
    visibility: visible;
    opacity: 1;
    height: auto;
    margin-top: 9px;
}

.dropdown-menu {
    display: block;
    visibility: hidden;
    opacity: 0;
    margin-top: 0;
    transition: 0.25s;
}