disable remove default css style sheet on Drupal 6

/www/drupal6/sites/all/themes/zen_test/template.php:

function zen_test_preprocess_page(&$vars, $hook) {
  foreach ($vars['css']['all']['module'] as $_k => $_v) {
    if (in_array($_k, array('not_yet'))) {
      continue;
    }

    unset($vars['css']['all']['module'][$_k]);

    $vars['styles'] = drupal_get_css($vars['css']);
  }
}