<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<div class="container">
<div class="row">
<div class="col-sm-6 col-sm-offset-3">
<div id="imaginary_container">
<div class="input-group stylish-input-group">
<input type="text" class="form-control" placeholder="Search" >
<span class="input-group-addon">
<button type="submit">
<span class="glyphicon glyphicon-search"></span>
</button>
</span>
</div>
</div>
</div>
</div>
</div>