anchor.diff:  
   <div class="section" id="contact">
     <h3 class="centered">Contact
  -    <a href="#"class="back_top">to the top ^</a>
  +    <a href="#" class="back_top">to the top ^</a>
     </h3>
   </div>
  
positive.code: <div class="section" id="venue">
    <div class="centered">
      <h3>Venue
        <a href="#"class="back_top">to the top ^</a>
      </h3>
  
      <h4>
  
negative.code: 
  <div class="section" id="speakers">
    <h3 class="centered">Speakers
      <a href="#" class="back_top">to the top ^</a>
    </h3>
    <ul class="centered">
      <li>
  