agaric-coop/web/themes/custom/agarica/agarica.theme

<?php

// TODO: Make this file unnecessary because we will not allow deploying code to the platform

/**
 * @file
 * Theme functions.
 */

/**
 * Implements hook_library_info_alter().
 */
function agarica_library_info_alter(&$libraries, $extension) {
  if ($extension === 'bulma' && isset($libraries['global'])) {
    // Since the replaced library files are no longer located in a directory
    // relative to the original extension, specify an absolute path (relative
    // to DRUPAL_ROOT / base_path()) to the new location.
    $css_file = '/' . drupal_get_path('theme', 'agarica') . '/styleguide/assets/css/agaric.css';
    $libraries['global']['css']['base'] = [
      $css_file => [],
    ];
  }
}

/**
 * Implements hook_theme_suggestions_HOOK_alter for blocks.
 *
 * See "Inheriting Block Templates" in
 * https://www.drupal.org/docs/8/theming-drupal-8/creating-a-drupal-8-sub-theme-or-sub-theme-of-sub-theme
 */
function family_home_theme_suggestions_block_alter(&$suggestions, $variables) {

  // Load theme suggestions for blocks from parent theme.
  foreach ($suggestions as &$suggestion) {
    $suggestion = str_replace('family_home_', 'octavia_', $suggestion);
  }
}