title: 2 Column layout, how to apply border such that taller div dictates border height
body: <p>I have a two-column layout ... and the design requires a border dividing them. I'm confused, where to apply the border (to the left one) or the right one, but it needs to be dynamic depending on which has more content.</p>
  
  <p>Do I have to resort to a container div? Does somebody have an example? I'm trying to adapt examples of backgrounds to do this, but to no avail.</p>