wp_enqueue_global_styles()

2559function wp_enqueue_global_styles() {2560	$assets_on_demand = wp_should_load_block_assets_on_demand();2561	$is_block_theme   = wp_is_block_theme();2562	$is_classic_theme = ! $is_block_theme;2563 2564	/**2565	 * Global styles should be printed in the HEAD for block themes, or for classic themes when loading assets on2566	 * demand is disabled (which is no longer the default since WordPress 6.9).2567	 *2568	 * @link https://core.trac.wordpress.org/ticket/534942569	 * @link https://core.trac.wordpress.org/ticket/619652570	 */2571	if (2572		doing_action( 'wp_footer' ) &&2573		(2574			$is_block_theme ||2575			( $is_classic_theme && ! $assets_on_demand )2576		)2577	) {2578		return;2579	}2580 2581	/**2582	 * The footer should only be used for classic themes when loading assets on demand is enabled. In WP 6.9 this is the2583	 * default with the introduction of hoisting late-printed styles (via {@see wp_load_classic_theme_block_styles_on_demand()}).2584	 * So even though the main global styles are not printed here in the HEAD for classic themes with on-demand asset2585	 * loading, a placeholder for the global styles is still enqueued. Then when {@see wp_hoist_late_printed_styles()}2586	 * processes the output buffer, it can locate the placeholder and inject the global styles from the footer into the2587	 * HEAD, replacing the placeholder.2588	 *2589	 * @link https://core.trac.wordpress.org/ticket/640992590	 */2591	if ( $is_classic_theme && doing_action( 'wp_enqueue_scripts' ) && $assets_on_demand ) {2592		if ( has_action( 'wp_template_enhancement_output_buffer_started', 'wp_hoist_late_printed_styles' ) ) {2593			wp_register_style( 'wp-global-styles-placeholder', false );2594			wp_add_inline_style( 'wp-global-styles-placeholder', ':root { --wp-internal-comment: "Placeholder for wp_hoist_late_printed_styles() to replace with the global-styles printed at wp_footer." }' );2595			wp_enqueue_style( 'wp-global-styles-placeholder' );2596		}2597		return;2598	}2599 2600	/*2601	 * If loading the CSS for each block separately, then load the theme.json CSS conditionally.2602	 * This removes the CSS from the global-styles stylesheet and adds it to the inline CSS for each block.2603	 * This filter must be registered before calling wp_get_global_stylesheet();2604	 */2605	add_filter( 'wp_theme_json_get_style_nodes', 'wp_filter_out_block_nodes' );2606 2607	$stylesheet = wp_get_global_stylesheet();2608 2609	/*2610	 * For block themes, merge Customizer's custom CSS into the global styles stylesheet2611	 * before the global styles custom CSS, ensuring proper cascade order.2612	 * For classic themes, let the Customizer CSS print separately via wp_custom_css_cb()2613	 * at priority 101 in wp_head, preserving its position at the end of the <head>.2614	 */2615	if ( $is_block_theme ) {2616		/*2617		 * Dequeue the Customizer's custom CSS2618		 * and add it before the global styles custom CSS.2619		 */2620		remove_action( 'wp_head', 'wp_custom_css_cb', 101 );2621 2622		/*2623		 * Get the custom CSS from the Customizer and add it to the global stylesheet.2624		 * Always do this in Customizer preview for the sake of live preview since it be empty.2625		 */2626		$custom_css = trim( wp_get_custom_css() );2627		if ( $custom_css || is_customize_preview() ) {2628			if ( is_customize_preview() ) {2629				/*2630				 * When in the Customizer preview, wrap the Custom CSS in milestone comments to allow customize-preview.js2631				 * to locate the CSS to replace for live previewing. Make sure that the milestone comments are omitted from2632				 * the stored Custom CSS if by chance someone tried to add them, which would be highly unlikely, but it2633				 * would break live previewing.2634				 */2635				$before_milestone = '/*BEGIN_CUSTOMIZER_CUSTOM_CSS*/';2636				$after_milestone  = '/*END_CUSTOMIZER_CUSTOM_CSS*/';2637				$custom_css       = str_replace( array( $before_milestone, $after_milestone ), '', $custom_css );2638				$custom_css       = $before_milestone . "\n" . $custom_css . "\n" . $after_milestone;