WP_Style_Engine_Processor::add_rules( WP_Style_Engine_CSS_Rule|WP_Style_Engine_CSS_Rule[] $css_rules ): WP_Style_Engine_Processor

68	public function add_rules( $css_rules ) {69		if ( ! is_array( $css_rules ) ) {70			$css_rules = array( $css_rules );71		}72 73		foreach ( $css_rules as $rule ) {74			$selector    = $rule->get_selector();75			$rules_group = $rule->get_rules_group();76 77			/**78			 * If there is a rules_group and it already exists in the css_rules array,79			 * add the rule to it.80			 * Otherwise, create a new entry for the rules_group.81			 */82			if ( ! empty( $rules_group ) ) {83				if ( isset( $this->css_rules[ "$rules_group $selector" ] ) ) {84					$this->css_rules[ "$rules_group $selector" ]->add_declarations( $rule->get_declarations() );85					continue;86				}87				$this->css_rules[ "$rules_group $selector" ] = $rule;88				continue;89			}90 91			// If the selector already exists, add the declarations to it.92			if ( isset( $this->css_rules[ $selector ] ) ) {93				$this->css_rules[ $selector ]->add_declarations( $rule->get_declarations() );94				continue;95			}96			$this->css_rules[ $rule->get_selector() ] = $rule;97		}98 99		return $this;100	}