Closes #11 by providing an initial design for the action option, getter, and setter
Closes #12 by deciding only to accept text; use the innerHTML setter to set HTML.
Closes #21 by settling on a specific content model and chosing the slot="action" attribute pattern.
Closes #11 by providing an initial design for the action option, getter, and setter Closes #12 by deciding only to accept text; use the innerHTML setter to set HTML. Closes #21 by settling on a specific content model and chosing the slot="action" attribute pattern.