Hi Rishabh, Your addon is fine but at startup, browser window(google.com/) is too bad prepared; İt's changeing,
and This dark google main window's display must be stabil, your's is changing badly. I expect you can correct it.Thank you,Health your hands(İn Turkish: Eline sağlık).

You/we should distinguish visited links from non-visited (different color).
Please, check google search and darken white ribbon when scrolling. Google translate has a big white annoying ribbon... But all and all, great extension.