form.html.erb

<%= form_for(@country) do |f| %>
  <% if @country.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@country.errors.count, "error") %> prohibited this country from being saved:</h2>

      <ul>
      <% @country.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>
  
  <div id="demo-form" class="demo-description" style="display: none; ">
  <p>
    The basic dialog window is an overlay positioned within the viewport and is protected from page content
    (like select elements) shining through with an iframe. It has a title bar and a content area, and can be moved,
    resized and closed with the 'x' icon by default.
  </p>
</div>

<%=  link_to_modal "Demo Form", "#demo-form", :class=>"button" %>

  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>
  <div class="field">
    <%= f.label :country_code %><br>
    <%= f.text_field :country_code %>
  </div>
  <div class="field">
    <%= f.label :currency_name %><br>
    <%= f.text_field :currency_name %>
  </div>
  <div class="field">
    <%= f.label :currency_code %><br>
    <%= f.text_field :currency_code %>
  </div>
  <div class="field">
    <%= f.label :rate %><br>
    <%= f.text_field :rate %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

has this error in browser console instead
GET http://localhost:3000/images/close 404 (Not Found)