Why is the content in the page not inverting in colour?(solved)

Question

I am doing everything right but it is not working. Why???!!!!
https://code.sololearn.com/W5OKsj82X2O4/?ref=app

Answer 1

Line 8, 9,11,12:
You mistake in syntax:

object.style.color
object.style.background

https://code.sololearn.com/WY5DAIx6adAs/?ref=app