Thread:Technobliterator/@comment-4041822-20161229180307/@comment-24485939-20161230141157

I couldn't help but let this catch my curiosity. I gave my hand a try.

What I've changed:
 * Moved the class from the wrapper element into the table
 * Gave the first header cell a height variable equal to the table's height. Otherwise it will be squeezed when expanded/collapsed. Remove that if it is intentional.

Regarding the vertical lines, the problem is the borders of the data cells, and the border "tables" inside the cells are not filling the entire table cells they reside in. Specially in height.