Include Agaric styleguide CSS in global library

Taken from Rosemary and Nedjo's work in

https://gitlab.com/uc-davis/patient-hm-brain/blob/master/web/themes/custom/henry/henry.theme
07981c439dfbf390abe047a7a95b053ffe4522cb

web/themes/custom/agarica/agarica.theme

@@ -2,6 +2,25 @@
 
 // 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.