Dropdowns as Panels.

[Daltz333]

TLDR: Ability to style dropdowns similar as panels.

My goal is to have 3 dropdowns in a row/column fashion. This is currently only possible when nested inside of a card, but this does not look aesthetically pleasing when 6 cards have only dropdowns in their content.

[Daltz333]

Alternatively, expandable panels would be acceptable.

[chrisjsewell]

This will essentially be closed by executablebooks/sphinx-design#6