anchor.diff:        </div>
       </div>
   
  -
       <%= f.fields_for :volume_costs do |vc_builder| %>
         <div class="form-group row">
           <label class="col-1 col-form-label"><%= vc_builder.label "Volume" %></label>
  
positive.code: <div class="container">
    <%= form_for(@product) do |f| %>
  
      <div class="form-group row">
        <label class="col-1 col-form-label"><%= f.label :name %></label>
  
negative.code:         <%= vc_builder.number_field :cost %>
        </div>  
      <% end %>
  
      <div class="actions">
        <%= f.submit %>
  