JSFiddle - React, Tailwind, and code Playground

HTML

<!-- Split button -->
<div class="btn-group btn-group-left">
    <button type="button" class="btn btn-danger dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"> <span class="caret"></span>
 <span class="sr-only">Toggle Dropdown</span>

    </button>
    <button type="button" class="btn btn-danger">Actions</button>
    <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 role="separator" class="divider"></li>
        <li><a href="#">Separated link</a>
        </li>
    </ul>
</div>

CSS

.btn-group.btn-group-left .dropdown-toggle {
    border-top-right-radius: 0px !important;
    border-bottom-right-radius: 0px !important;
}
.btn-group.btn-group-left .dropdown-toggle+.btn {
    border-top-right-radius: 4px !important;
    border-bottom-right-radius: 4px !important;
}