JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css">
<div class="btn-group" id="sortBtns" role="group">
    <button type="button" class="btn btn-default">First</button>
    <button type="button" class="btn btn-default">Second</button>
    <button type="button" class="btn btn-default">Third</button>
    <button type="button" class="btn btn-default">Fourth</button>
    <button type="button" class="btn btn-default">Fifth</button>
    <button type="button" class="btn btn-default">Sixth</button>
</div>

<p>&nbsp;</p>

<div class="btn-group" id="sortBtns" role="group">
    <button type="button" class="btn btn-default">First</button>
    <button type="button" class="btn btn-default">Second</button>
    <button type="button" class="btn btn-default">Third</button>
    <button type="button" class="btn btn-default">Fourth</button>
    <button type="button" class="btn btn-default">Fifth</button>
    <button type="button" class="btn btn-default" style="display:none;">Sixth</button>
</div>

<p>
    Note the lack of rounded corners on 'fifth' in the second button group.
</p>

CSS

.btn-group{
    margin-left:5px;
    margin-top:5px;
}