public function submitForm(array &$form, FormStateInterface $form_state) {
parent::submitForm($form, $form_state);
$enabled_styles = array_keys(array_filter((array) $form_state
->getValue('styles'), function ($value) {
return !empty($value['enabled']);
}));
$this->config
->set('enabled_styles', $enabled_styles);
$this->config
->save();
}