JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<div class="container"><div class="row">
<div class="span3 btn-group">
    <button class="btn">one</button>
    <button class="btn">two</button>
    <button class="btn">three</button>
</div>
<div class="span3 btn-group">
    <a class="dropdown-toggle btn" data-toggle="dropdown" href="#">one <span class="caret"></span></a>
    <ul class="dropdown-menu">
        <li><a href="#">Action</a></li>
        <li><a href="#">Another action</a></li>
        <li><a href="#">Something else here</a></li>
        <li class="divider"></li>
        <li><a href="#">Separated link</a></li>
    </ul>
    <button class="btn">two</button>
    <button class="btn">three</button>
</div>
<div class="span3 btn-group">
    <button class="btn">one</button>
    <a class="dropdown-toggle btn" data-toggle="dropdown" href="#">two <span class="caret"></span></a>
    <ul class="dropdown-menu">
        <li><a href="#">Action</a></li>
        <li><a href="#">Another action</a></li>
        <li><a href="#">Something else here</a></li>
        <li class="divider"></li>
        <li><a href="#">Separated link</a></li>
    </ul>
    <button class="btn">three</button>
</div>
<div class="span3 btn-group">
    <button class="btn">one</button>
    <button class="btn">two</button>
    <a class="btn dropdown-toggle" data-toggle="dropdown" href="#">three <span class="caret"></span></a>
    <ul class="dropdown-menu">
        <li><a href="#">Action</a></li>
        <li><a href="#">Another action</a></li>
        <li><a href="#">Something else here</a></li>
        <li class="divider"></li>
        <li><a href="#">Separated link</a></li>
    </ul>
    
</div>
</div></div>

CSS

.btn-group > .dropdown-toggle {
    border-bottom-right-radius: 0px;
    border-top-right-radius: 0px;
    margin-right: -1px;
    }
.btn-group > .btn:last-child, .btn-group > .dropdown-toggle:nth-last-child(2) {
    border-bottom-right-radius: 4px;
    border-top-right-radius: 4px;
    }