Edge of div is cracking on rotation..help to fix

Question

The edge of rotating div is cracking/not smooth at some angle of rotation. See a complete rotation.help to fix. Better if explain...code 👇
https://code.sololearn.com/WMOwouBj3zG7/?ref=app

Answer 1

https://code.sololearn.com/WT5Dlv5w51jr/?ref=app

see this

Answer 2

I appreciate your response guys, but these are alternatives/tricks to solve it. I'm looking for solution and its actual cause.....