JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<!--

Custom HTML : add a "group-dropdown" class to the dropdown
"btn-group" div.
The "btn-group" div must wrap the whole button (button+submenu items), as specified in the bootstrap doc. This allows you to put several dropdowns in the same buttons group.

Works whatever their position in the button group is.

-->

<!---
Here starts the button group
-->
<div class="btn-group">
    <!--First dropdown : note the "group-dropdown" property -->
    <div class="btn-group group-dropdown">
        <a class="btn btn-mini dropdown-toggle" data-toggle="dropdown" href="#" title="Filter by">
            <i class="icon icon-filter"></i>
            <span class="caret"></span>
        </a>
        <ul class="dropdown-menu">
            <li><a href="#">All</a></li>
            <li><a href="#">...</a></li>
        </ul>
    </div>
    
    <!-- Classic button -->
    <a href="#" class="btn btn-mini" title="New">
        <i class="icon-plus-sign"></i>
    </a>
    
    <!-- Classic button -->
    <a href="#" class="btn btn-mini" title="Import">
        <i class="icon-upload"></i>
    </a>
    
    <!-- Dropdown in the middle of the button group -->
    <div class="btn-group group-dropdown">
        <a class="btn btn-mini dropdown-toggle" data-toggle="dropdown" href="#" title="Export">
            <i class="icon icon-download"></i>
            <span class="caret"></span>
        </a>
        <ul class="dropdown-menu">
            <li><a href="#">.csv file</a></li>
            <li><a href="#">.json file</a></li>
            <li><a href="#">.ods file</a></li>
            <li><a href="#">.xml file</a></li>
            <li><a href="#">.sql file</a></li>
        </ul>
    </div>
    
    <!-- Dropdown at the end of the button group -->
    <div class="btn-group group-dropdown">
        <a class="btn btn-mini dropdown-toggle" data-toggle="dropdown" href="#" title="Another action">
            <i...

CSS

/*

Twitter Bootstrap CSS modifications for having dropdown menus in
buttons groups.
Dropdowns menus are well positionned, under their buttons.

LESS code at bottom

Kure2012.

*/
.btn-group.group-dropdown {
  margin: 0px;
  padding: 0px;
  margin-left: -1px;
}
.btn-group.group-dropdown .dropdown-toggle {
  -webkit-border-radius: 0;
  -moz-border-radius: 0;
  border-radius: 0;
}
.btn-group.group-dropdown:first-child {
  margin: 0px;
  padding: 0px;
  margin-right: -1px;
}
.btn-group.group-dropdown:first-child .dropdown-toggle {
  -webkit-border-top-left-radius: 4px;
  -moz-border-radius-topleft: 4px;
  border-top-left-radius: 4px;
  -webkit-border-bottom-left-radius: 4px;
  -moz-border-radius-bottomleft: 4px;
  border-bottom-left-radius: 4px;
}
.btn-group.group-dropdown:first-child .dropdown-toggle.btn-large {
  -webkit-border-top-left-radius: 6px;
  -moz-border-radius-topleft: 6px;
  border-top-left-radius: 6px;
  -webkit-border-bottom-left-radius: 6px;
  -moz-border-radius-bottomleft: 6px;
  border-bottom-left-radius: 6px;
}
.btn-group.group-dropdown:last-child {
  margin: 0px;
  padding: 0px;
  margin-left: -1px;
}
.btn-group.group-dropdown:last-child .dropdown-toggle {
  -webkit-border-top-right-radius: 4px;
  -moz-border-radius-topright: 4px;
  border-top-right-radius: 4px;
  -webkit-border-bottom-right-radius: 4px;
  -moz-border-radius-bottomright: 4px;
  border-bottom-right-radius: 4px;
}
.btn-group.group-dropdown:last-child .dropdown-toggle.btn-large {
  -webkit-border-top-right-radius: 6px;
  -moz-border-radius-topright: 6px;
  border-top-right-radius: 6px;
  -webkit-border-bottom-right-radius: 6px;
  -moz-border-radius-bottomright: 6px;
  border-bottom-right-radius: 6px;
}

/* And the LESS Code :
.btn-group{
    &.group-dropdown{
        margin:0px;
        padding:0px;
        margin-left:-1px;
        .dropdown-toggle{
            .border-radius(0);
        }
        &:first-child{
            margin:0px;
            padding:0px;
           ...