Theming whole modal form with custom class

In the previous post I wrote about the way to create custom modal form sizes. This time I will add a class to each window, so you can also theme them totally. Currently by default there are only generic classes and you can make one header of modal form different then the other. You can only theme form part as form element has unique class. As in former post I created
http://drupaldump.com/creating-custom-forms-modal-forms custom settings in modal_forms_js_settings alter function for each of my modals, what I will add here is also custom settings 'styleCss' => 'login-form', which in the end will be passed to modal-forms-popup.js

function my_module_modal_forms_js_settings_alter(&$js_settings){

  $js_settings['modal-popup-login'] = array(
      'modalSize' => array(
        'type' => variable_get('modal_forms_popup_extra_type', 'fixed'),
        'width' => floatval(variable_get('modal_forms_popup_extra_width', 402)),
        'height' => floatval(variable_get('modal_forms_popup_extra_height', 460)),
        'contentBottom' => 0,
        'contentRight' => 0,
      ),
      'modalOptions' => array(
        'opacity' => floatval(variable_get('modal_forms_opacity', 0.83)),
        'background' => variable_get('modal_forms_background_color', '#000'),
      ),
      'animation' => 'fadeIn',
      'modalTheme' => 'ModalFormsPopup',
      'styleCss' => 'login-form',
      'throbber' => $throbber,
      'closeText' => t('Close'),
    );
}

so it is passed here when html is created, so this way you can target each modal window and theme it to your liking.

Drupal.theme.prototype.ModalFormsPopup = function () {
  var html = '';

  html += '
'; html += '