public function remove_empty_rulelist() { foreach ($this->document->getContents() as $item) { if ($item instanceof CSS\CSSList\AtRuleBlockList) { /* @var $item CSS\CSSList\AtRuleBlockList */ foreach ($item->getContents() as $rule_sets) { if (empty($rule_sets->getRules())) { $item->remove($rule_sets); } } if (empty($item->getContents())) { $this->document->remove($item); } } } }