The ".collapse" class is used to specify the collapsible element. Flexible plugin that utilizes a handful of classes for easy toggle behavior. Click on the button to
toggle between showing and hiding content.
.collapse hides content
.collapsing is applied during transitions
.collapse.in shows content
You can use a link with the href attribute, or a button with the data-target attribute. In both cases, the data-toggle="collapse" is required.