Displays and hides large additional content on demand.

[%<div-more>
  <div>Teaser text</div>
  <div>More text</div>
  <dm-control>
     <button dm-opener>Read more</button>
     <button dm-closer>Read less</button>
  </dm-control>
</div-more>%]

The element %div-more% requires two children. The first one is *always visible*. The second child *becomes visible* when the %dm-opener% is clicked and closes when %dm-closer% is clicked.