= f.input :url, required: true, wrapper_html:{class: f.object.errors.messages[:slug] ? "error" : nil}, hint: f.object.root? ? "This page is your home page" : nil do
  - if f.object.root?
    .btn(disabled)=> "/" 
    ' or
  .input-prepend style="display:inline"
    = f.select :parent_url, options_for_select(@page.parent_url_options, f.object.parent_url)
    / .add-on
    /   - if @page.new_record?
    /     = f.select :parent_url, options_for_select(@page.parent_url_options, f.object.parent_url)
    /   - else
    /     = f.object.parent_url

    = f.text_field :slug

  br
  = f.error :slug