<div class="btn-group">
    <button type="button" class="btn btn-danger">left</button>
    <button type="button" class="btn btn-warning">middle</button>
    <button type="button" class="btn btn-success">right</button>
</div>
                

<div class="btn-group">
    <button type="button" class="btn btn-outline-primary">left</button>
    <button type="button" class="btn btn-outline-primary">middle</button>
    <button type="button" class="btn btn-outline-primary">right</button>
</div>
                

<div class="btn-group">
    <button type="button" class="btn btn-sm btn-outline-primary">small</button>
    ...
</div>
<div class="btn-group">
    <button type="button" class="btn btn-outline-primary">normal</button>
    ...
</div>
<div class="btn-group">
    <button type="button" class="btn btn-lg btn-outline-primary">large</button>
    ...
</div>
                

<div class="btn-group btn-group-vertical">
    <button type="button" class="btn btn-outline-primary">top</button>
    <button type="button" class="btn btn-outline-primary">middle</button>
    <button type="button" class="btn btn-outline-primary">bottom</button>
</div>