Combine sets of <div class="btn-group">
into a <div class="btn-toolbar">
for more complex components.
<div class="btn-toolbar" role="toolbar" aria-label="...">
<div class="btn-group" role="group" aria-label="...">...</div>
<div class="btn-group" role="group" aria-label="...">...</div>
<div class="btn-group" role="group" aria-label="...">...</div>
</div>