The Current implementation of element provides a button role. Not sure if this is sufficient from the understandings at: http://accessibleculture.org/articles/2012/03/screen-readers-and-details....
As is not accessible on all browsers,To polyfill for accessibility we need to:
1) set tabindex ="0" - make it keyboard focusable
2) assign ARIA role button -> DONE!
3) aria-expanded attribute that changes based on state
4) non-summary content to be hidden by using dispaly:none when elements are collapsed
5) Any links within summary could be confusing (Not applicable in this case)