anchor.diff:      </section>
   
       <!-- Callout -->
  +    <section id="costs" class="costs">
       <aside class="callout">
           <div class="text-vertical-center">
               <h1>Lesson Costs:</h1>
  
positive.code:             <h2>Voice: $25/hr</h2>
          </div>
      </aside>
  
      <!-- Portfolio -->
      <section id="portfolio" class="portfolio">
  
negative.code:                                     <strong>Voice</strong>
                                  </h4>
                                  <p>I offer voice lessons for... etc.</p>
                                  <a href="#costs" class="btn btn-light">Learn More</a>
                              </div>
                          </div>
  
  