public function postmessage() {
		wp_enqueue_script( 'kirki_auto_css_vars', URL::get_from_path( __DIR__ . '/script.js' ), [ 'jquery', 'customize-preview' ], KIRKI_VERSION, true );
		$fields = array_merge( Kirki::$fields, $this->fields );
		$data   = [];
		foreach ( $fields as $field ) {
			if ( isset( $field['transport'] ) && 'postMessage' === $field['transport'] && isset( $field['css_vars'] ) && ! empty( $field['css_vars'] ) ) {
				$data[] = $field;
			}
		}
		wp_localize_script( 'kirki_auto_css_vars', 'kirkiCssVarFields', $data );
	}