anchor.diff:    font-weight: bold;
   }
   
  +.content {
  +  font-family: monospace;
  +  /* Vertical margin around content. */
  +  margin: 1em 0;
  +  /* Offset the margin introduced by the absolutely positioned child div. */
  +  margin-left: -0.5em;
  +  position: relative;
  +  white-space: pre;
  +}
  +
   .code {
     left: 0.5em;
     /* Increase line height to make room for borders in non-nullable type
  
positive.code:    */
    line-height: 1.3;
    padding-left: 60px;
    position: absolute;
    top: 0.5em;
  }
  
  .content {
    font-family: monospace;
    position: relative;
    white-space: pre;
  }
  
  .regions {
  
negative.code:     '{{! the content, to provide tooltips for modified regions. }}'
      '{{{ regionContent }}}'
      '</div></div>'
      '<div>Footer</div>'
      r'''
      {{/ units }}
      <script lang="javascript">
  