It's not based on skin color, but it often is that low caste are darker. That being you totally have dark skinned high caste and light skinned low caste people.

Racism is definitely there culturally in India, but it's complicated on who they considered superior and who is inferior, like Middle Easterners are fairer but Indians would think they are inferior, while same white boiis of Europe are equal or superior. It's very weird. I think we as humans just don't want to get along with each other just take a shit on someone all the time.