@pearl your essay is quite fine....the only thing which i wana add is to avoid going into the history as most of the css checkers dn't recommend it...I have read with several css checkers,they were strongly against historical background.whenever i wrote hist. Background they used to cut that portion out..hahaha...however,just write a para not more than that.Also, try to write as simple as possible,usage of difficult and complex words will never help you to fetch good marks.And yes,are you a repeater ?if yes,in which paper or papers you got failed while appearing for the first time?