What is webkit ?

Answer 1

this is an css attribute which is used to style on Opera browser specifically.

Answer 2

@Siddharth Saraf wrote: "this is an css attribute which is used to style on Opera browser specifically."

The name is used as vendor prefix ( with dashes before and after: -webkit- ) on some css property ( but it isn't itself a property )to target navigators using this engine...
Opera don't use webkit, they have their own engine, and specific css properties for Opera are prefixed -o-.

Answer 3

https://en.m.wikipedia.org/wiki/WebKit