Bootstrap CSS border radius on first btn in group

In bootstrap 3, I have a button group. If the first item in the button group has a hidden class, the first visible element loses it's rounded border radius.

How can I modify the CSS below so that if the first element has a hidden class, the first visible element should still have the rounded corners on the left?

 body{padding:20px}
.btn-group > .btn:not(:first-child):not(:last-child):not(.dropdown-toggle) {
  border-radius: 0;
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet"/>
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.6.3/css/font-awesome.min.css" rel="stylesheet"/>

<div role="group" class="btn-group btn-group-sm" id="preview-paging">
  <div role="group" class="btn-group hidden" id="preview-type">
    <button data-toggle="dropdown" class="btn btn-default btn-sm dropdown-toggle" type="button">
      <span id="preview-label">Desktop</span>
      <span class="caret"></span>
    </button>
    <ul class="dropdown-menu">
      <li><a data-device="desktop" href="#design">Desktop</a></li>
      <li><a data-device="mobile" href="#design">Mobile</a></li>
    </ul>
  </div>
  <div class="btn btn-default btn-sm btn-paging" id="preview-prev"><i class="fa fa-chevron-left"></i></div>
  <div class="btn btn-default btn-sm btn-paging" id="preview-next"><i class="fa fa-chevron-right"></i></div>
</div>