anchor.diff:    <% @course.sections.each do |s| %>
     #submissions.show_one .sec_<%= s.crn %> { display: none; }
     #submissions.show_one.sec_<%= s.crn %> .sec_<%= s.crn %> { display: table-row; }
  +
  +  #number-submissions.show_one .sec_<%= s.crn %> { display: none; }
  +  #number-submissions.show_one.sec_<%= s.crn %> .sec_<%= s.crn %> { display: block; }
  +  #number-submissions.show_all .sec_<%= s.crn %> { display: none; }
     <% end %>
  +  #number-submissions.show_one .all { display: none; }
   </style>
   <% end %>
   <div style="display: flex; flex-direction: row; align-items: baseline; justify-content: space-between;">
  
positive.code:     $(function() {
        var prevSection = "show_all";
        $("#sections").change(function(e) {
          $("#submissions").removeClass(prevSection).addClass($(this).val());
          prevSection = $(this).val();
        });
  
negative.code:     <% end %>
    </select>
  </h4>
  <div id="number-submissions" class="show_all">
    <h3 class="all">
      <p>All Sections</p>
      <%= type[:noun].pluralize(2).capitalize %> (<%= @gradesheet.submissions.count %> / <%= @course.students.length %>)
    </h3>
    <% @course.sections.each do |s| %>
    <h3 class="sec_<%= s.crn %>">
      <p><%= s.to_s %></p>
      <% sec_students_submitted = @gradesheet.submissions.select{|sub| s.users.include?(sub.user)}.length %>
      <%= type[:noun].pluralize(2).capitalize %> (<%= sec_students_submitted %> / <%= s.students.length %>)
    </h3>
    <% end %>
  </div>
  <% end %>
    <table id="submissions" class="table table-striped row-vcenter">
      <thead>
  