If I were to try it, I would absolute position the button to be close to the bottom of the column. That would create a potential problem where, if there is too much content in the column, text could flow down and collide with the button. To fix that I would put enough padding on the bottom of the container of the text so any additional text would force the column to go longer before it ever came in contact with the button. For example, if the top of the button were 60px from the bottom of the column, and I wanted to have a 30px space above it, I would have padding-bottom:90px, or 9em or 9rem, etc. on the container. The button would sit in the cushion of padding and the text would never touch it. I assume you have some method for making the columns the same height.
I would love to know how someone else would approach this.
