Processor is great but it only supports JS convention at the moment. When I generate compressed CSS with dart-sass, sourcemapping URL comment looks like following ( ```/*# sourceMappingURL=application.css.map */``` Unfortunately, its not taken into account by [current preprocessor](https://github.com/rails/sprockets-rails/blob/0a56eec89d86d7ef36af439bad7df51adbc575c5/lib/sprockets/rails/sourcemapping_url_processor.rb), which expects JS syntax (```//# sourceMappingURL```) both in [parsing](https://github.com/rails/sprockets-rails/blob/0a56eec89d86d7ef36af439bad7df51adbc575c5/lib/sprockets/rails/sourcemapping_url_processor.rb#L5) and in [generation](https://github.com/rails/sprockets-rails/blob/0a56eec89d86d7ef36af439bad7df51adbc575c5/lib/sprockets/rails/sourcemapping_url_processor.rb#L34)