anchor.diff:  
   .content {
     font-family: monospace;
  +  position: relative;
     white-space: pre;
  -}
  -
  -.content.highlighting {
  -  position: relative;
   }
   
   .regions {
     position: absolute;
  +  left: 0.5em;
     top: 0.5em;
     /* The content of the regions is not visible; the user instead will see the
      * highlighted copy of the content. */
  
positive.code:   border: solid 2px #999;
    color: #333;
    cursor: auto;
    left: 50%;
    margin-left: -100px;
    padding: 1px;
    position: absolute;
    top: 100%;
    visibility: hidden;
    width: 200px;
    z-index: 1;
  }
  
negative.code:       {{/ links }}
      </div>
      {{# units }}'''
      '<h2>{{{ path }}}</h2>'
      '<div class="content">'
      '<div class="highlighting">'
      '{{! These regions are written out, unmodified, as they need to be found }}'
      '{{! in one simple text string for highlight.js to hightlight them. }}'
      '{{# regions }}'
      '{{ content }}'
      '{{/ regions }}'
      '</div>'
      '<div class="regions">'
      '{{! The regions are then printed again, overlaying the first copy of the }}'
      '{{! content, to provide tooltips for modified regions. }}'
      '{{# regions }}'
  