set column border until bottom

Hi Tom,

Thanks for the answer. In the linked topic I only could find a code for the borders between columns of the second level. Is there a way to extend this code to the third level?

Also, is it possible to apply the lines only between the columns and not on the outer sides? If I use left or right border of the columns, either way there is an extra line on the left or the right end which is not needed.