wp_render_custom_css_support_styles( array $parsed_block ): array

41function wp_render_custom_css_support_styles( $parsed_block ) {42	$custom_css = $parsed_block['attrs']['style']['css'] ?? null;43	if ( ! is_string( $custom_css ) || '' === trim( $custom_css ) ) {44		return $parsed_block;45	}46 47	$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $parsed_block['blockName'] );48	if ( ! block_has_support( $block_type, 'customCSS', true ) ) {49		return $parsed_block;50	}51 52	// Validate CSS doesn't contain HTML markup (same validation as global styles REST API).53	if ( preg_match( '#</?\w+#', $custom_css ) ) {54		return $parsed_block;55	}56 57	// Generate a unique class name for this block instance.58	$class_name          = wp_unique_id_from_values( $parsed_block, 'wp-custom-css-' );59	$existing_class_name = $parsed_block['attrs']['className'] ?? null;60	$updated_class_name  = is_string( $existing_class_name )61		? "$existing_class_name $class_name"62		: $class_name;63 64	$parsed_block['attrs']['className'] = $updated_class_name;65 66	// Process the custom CSS using the same method as global styles.67	$selector      = '.' . $class_name;68	$processed_css = WP_Theme_JSON::process_blocks_custom_css( $custom_css, $selector );69 70	if ( ! empty( $processed_css ) ) {71		/**72		 * Reuse one handle so identical custom CSS is enqueued only once via73		 * {@see wp_unique_id_from_values()}. Explicitly declare the `wp-block-library`74		 * dependency so `global-styles` is guaranteed to print after it, preventing75		 * block default styles from unintentionally overriding global styles.76		 */77		$handle = 'wp-block-custom-css';78		if ( ! wp_style_is( $handle, 'registered' ) ) {79			wp_register_style( $handle, false, array( 'wp-block-library', 'global-styles' ) );80		}81		$after_styles = wp_styles()->get_data( $handle, 'after' );82		if ( ! is_array( $after_styles ) ) {83			$after_styles = array();84		}85		if ( ! in_array( $processed_css, $after_styles, true ) ) {86			wp_add_inline_style( $handle, $processed_css );87		}88	}89 90	return $parsed_block;91}