app/views/cases/_issue_fields.html.erb
<li class="list-group-item nested-fields">
<div class="row">
<div class="col-xs-10">
<%= f.input :tag_id, label: false do %>
<%= f.select :tag_id, Tag.all.collect { |tag| [ tag.name, tag.id ] }, include_blank: false %>
<% end %>
<%= f.input :description, label: false, input_html: { rows: 5 } %>
</div>
<div class="col-xs-2">
<%= link_to_remove_association "Remove", f, class: 'btn btn-danger btn-block', data: { confirm: "Are you sure?" } %>
</div>
</div>
</li>