src/ScssCompiler.php
public function css($file, $media = null)
    {
        $css_file = $this->processScssFile($file);
        return parent::css($css_file, $media);
    }
public function css($file, $media = null)
    {
        $css_file = $this->processScssFile($file);
        return parent::css($css_file, $media);
    }
Register the given stylesheet into the list of requirements.
Processes *.scss files if detected and rewrites URLs

@param string $file The CSS file to load, relative to site root
@param string $media Comma-separated list of media types to use in the link tag (e.g. 'screen,projector')