CSS validation issues

Hi there,
I noticed that the plugin’s file wp-rss-multi-importer/templates/templates.css causes some CSS validation issues with the W3C CSS Validator.
Most of them depend on the usage of // comments, which are not valid for CSS (it requires /* ... */ )

https://wordpress.org/plugins/wp-rss-multi-importer/