Collapsible

We will animate the size of a named collapsible whenever it's status changes. So don't change the visiblity of the collapsible container with CSS, but rather its children.

We will only allow one collapsible of group to be open (and auto-close all others). This will behave like an accordion.

It is very simple to open/close a collapsible via custom JS. Just change the data-hidden attribute and we take care of the rest.