anchor.diff:      <div class="card-columns">
         <% lecture.chapters.each do |c| %>
           <div class="card bg-mdb-color-lighten-5">
  -          <div class="card-header">
  -            <%= link_to c.to_label, chapter_path(c), class: 'text-dark' %>
  +          <div class="card-header bg-mdb-color-lighten-2">
  +            <span class="text-light">
  +              <%= c.to_label %>
  +            </span>
             </div>
             <div class="card-body">
             <ul class="list-group list-group-flush">
  
positive.code:               <li class="list-group-item bg-mdb-color-lighten-5">
                  <div class="row">
                    <div class="col-6">
                      <%= link_to s.to_label, section_path(s), class:'text-dark' %>
                    </div>
                    <div class="col-6">
                      <% s.lessons.each do |l| %>
  
negative.code: <div class="card bg-mdb-color-lighten-6">
    <div class="card-header">
      <h5>
        Vorlesungsinhalt
  