Source: dist/css/library_boot.css, line 7939
4.4.1.2 Collapse Toggle Advanced with Square
Toggle elements of a collapse with user feed back of the icon morphing.
Example s
#targetName
the name of the target of the collapse
<div class="flex_none" aria-expanded="false" data-bs-toggle="collapse" data-bs-target="[modifier]" aria-controls="[modifier]">
<span class="fa-stack">
<i class="fas fa-square fa-stack-2x"></i>
<i class="fas fa-minus fa-stack-1x c_white"></i>
<i class="fas fa-minus rotate_90 a:rotation fa-stack-1x c_white"></i>
</span>
</div>