@vinothkannans Thanks for answer.
But I had tried this after searching github repository. It didnt work for me, as the result was same as before.
I also tried another variation from this repo
register_asset('stylesheets/topiclist.scss', :desktop)
But this too didnt work.
I do not know Ruby very well, are the :desktop and :mobile variables available in plugin.rb file which control which stylesheet should be applicable?