Asset Manager set target path

I have a path in a private directory that I want to recreate in a public path. Here is an example of what I mean:

/application
        /public
                /assets
                index.php
        /themes
                /default
                        /css
                            style.css

I want to be able to create/publish, style.css in /public/assets/themes/default/css/style.css for public access. How can I achieve that with Asset Manager?

I have tried the following with no luck:

$di->set('assets', function() {
     $assets = new Phalcon\Assets\Manager([
          'output'=>realpath(__DIR__.'/assets/'),
          'compileAlways'=>false,
          'stat'=>true
      ]);
      return $assets;
});

  // controller
$css = new \Phalcon\Assets\Resource\Css('/assets/style.css');
$css->setSourcePath(realpath($this->view->getViewsDir().'/../../assets/style.css'));
$css->setTargetPath(APP_PATH.'/assets/style.css');
$css->setLocal(false);
$this->assets->addResourceByType('css', $css);

// view
$this->assets->outputCss();