CRM-12578 - Fix weight of custom css file

CRM/Core/Resources.php

@@ -491,7 +491,7 @@ class CRM_Core_Resources {
       // Load custom or core css
       $config = CRM_Core_Config::singleton();
       if (!empty($config->customCSSURL)) {
-        $this->addStyleUrl($config->customCSSURL, -99, $region);
+        $this->addStyleUrl($config->customCSSURL, 99, $region);
       }
       if (!CRM_Core_BAO_Setting::getItem(CRM_Core_BAO_Setting::SYSTEM_PREFERENCES_NAME, 'disable_core_css')) {
         $this->addStyleFile('civicrm', 'css/civicrm.css', -99, $region);