_form.html.erb

<%= form_with model: puzzle do |f| %>
  <div class="modal-area">
    <%= f.label :question %>
    <%= f.text_area :question, class: puzzle.errors[:question].any? ? "error" : "" %>
    <% if puzzle.errors[:question].any? %>
      <div class="field-error"><%= puzzle.errors[:question].first %></div>
    <% end %>
  </div>

<div class="modal-area">
  <%= f.label :answer %><br>
  <div class="answer-radio-group">
    <label>
      <%= f.radio_button :answer, "ruby" %> Ruby
    </label>
    <label>
      <%= f.radio_button :answer, "rails" %> Rails
    </label>
  </div>
</div>

  <div class="modal-area">
    <%= f.label :explanation %>
    <%= f.text_area :explanation %>
  </div>

  <div class="modal-area">
    <%= f.label :link %>
    <%= f.text_field :link %>
  </div>

  <%= f.submit "Save", class: "btn approve-btn" %>
<% end %>