index.erb

<style type="text/css">
body {
  background-color: rgb(255, 45, 45);
}


 table {
  margin-top: 50px;
  border-width: 0;
  border-style: none;
  border-color: #0000ff;
  border-collapse: collapse;
 }
 td {
   border-width: 0;
   border-style: none;
   border-color: #0000ff;
   border-collapse: collapse;
   padding: 0;
   margin: 0;
   width: 6px;
   height: 6px;
 }
 td.black { background-color: #000; }
 td.white { background-color: transparent; }
</style>
<center>
<div class="tag">
<table>
 <% @qr.modules.each_index do |x| %>
   <tr>
   <% @qr.modules.each_index do |y| %>
    <% if @qr.dark?(x,y) %>
    <td class="black"/>
    <% else %>
    <td class="white"/>
    <% end %>
   <% end %>
   </tr>
 <% end %>
</table>
</div>
</center>