SettingsTrayTestCssHooks.php

<?php

declare (strict_types=1);
namespace Drupal\settings_tray_test_css\Hook;

use Drupal\Core\Hook\Attribute\Hook;

/**
 * Hook implementations for settings_tray_test_css.
 */
class SettingsTrayTestCssHooks {
    
    /**
     * Implements hook_page_attachments().
     */
    public function pageAttachments(array &$attachments) : void {
        // Unconditionally attach an asset to the page.
        $attachments['#attached']['library'][] = 'settings_tray_test_css/drupal.css_fix';
    }

}