How to dequeue specific core block styles from the editor?

[germanfrelo]

Hi there.

I'm trying to remove a specific list of default block styles from both the front end and the block/site editor in my block theme.

I've been successful on the front end, but I can't get the same approach to work in the editor. The styles, specifically from wp-block-library, are always present, and I can only find methods to remove all core styles, not specific ones.

Environment

• WordPress Version: 6.8.3
• Gutenberg Plugin: Not Active
• PHP Version: 8.4.10
• Theme: A custom Block Theme
• Active Plugins: Tested with all other plugins disabled to rule out conflicts

Code I'm Using

Here is the full code I am currently using, which includes forcing separate asset loading and using enqueue_block_editor_assets with the latest possible priority:

/**
 * Force WordPress to load separate assets for each core block.
 */
add_filter('should_load_separate_core_block_assets', '__return_true');

/**
 * Get the list of core block style handles to remove.
 */
function themeslug_get_block_styles_to_remove() {
	return [
		// Main block library stylesheets.
		'wp-block-library',
		'wp-block-library-theme',

		// Specific block styles.
		'wp-block-categories',
		'wp-block-code',
		'wp-block-details',
		'wp-block-list',
		'wp-block-post-template',
		'wp-block-post-title',
		'wp-block-quote',
		'wp-block-read-more',
		'wp-block-search',
		'wp-block-site-logo',
		'wp-block-site-title',
	];
}

/**
 * Remove specific default block styles from the front end.
 */
function themeslug_remove_core_block_styles_from_frontend() {
	$handles = themeslug_get_block_styles_to_remove();
	foreach ($handles as $handle) {
		wp_dequeue_style($handle);
	}
}
add_action('wp_enqueue_scripts', 'themeslug_remove_core_block_styles_from_frontend', 100);


/**
 * Remove specific default block styles from the Block Editor and Site Editor.
 */
function themeslug_remove_core_block_styles_from_editor() {
	$handles = themeslug_get_block_styles_to_remove();
	foreach ($handles as $handle) {
		wp_dequeue_style($handle);
	}
}
// Using the latest possible priority to override dependencies.
add_action('enqueue_block_editor_assets', 'themeslug_remove_core_block_styles_from_editor', PHP_INT_MAX);

Despite these attempts, the styles persist in the editor. Am I missing a step, or is there a different, more modern approach to selectively removing core block styles from the editor context?

Any help would be appreciated!

[ashik4339]

The frontend half works because wp_enqueue_scripts runs in a normal document. The editor half doesn't work because since WordPress 6.3, the post/site editor canvas renders inside an iframe — and enqueue_block_editor_assets only affects the outer admin page (toolbar, sidebar), not the iframed canvas where block styles actually need to apply.

Fix: swap the editor half to enqueue_block_assets instead. Since 6.3, everything enqueued through that hook is mirrored into the iframe automatically:

function themeslug_remove_core_block_styles_from_editor() {
    if ( ! is_admin() ) {
        return; // enqueue_block_assets also fires on the frontend — avoid double-handling
    }
    $handles = themeslug_get_block_styles_to_remove();
    foreach ( $handles as $handle ) {
        wp_dequeue_style( $handle );
    }
}
add_action( 'enqueue_block_assets', 'themeslug_remove_core_block_styles_from_editor', PHP_INT_MAX );

Your should_load_separate_core_block_assets filter is correct and still needed (that's what makes per-block handles like wp-block-quote exist to dequeue in the first place) — the only broken piece was which hook fires inside the iframe.