Before going further, I would like to introduce you to Phalcon's assets manager. This is a very useful component when you need to handle lots of assets (in general, CSS files, images, and JavaScript files). The service should already be available, and you can access it via DI using the following command:

$manager = $this->assets;

Otherwise, you can use the following command:

$manager = $this->getDI()->get('assets');

$di->set('assets', function () {
    return new Phalcon\Assets\Manager();
}, true);

Now, let's open the main layout for the back office and do some changes. Open modules/Backoffice/Views/Default/layout.volt and remove all the lines containing stylesheetLink and javascriptInclude.

Now...