How to set the radius of the outline

Question

How to set the radius of the outline of an element as if it were the border

https://code.sololearn.com/WpSXuCf4c3KE/?ref=app

Answer 1

Border-radius: Controls the radius of the border and the outline.

https://code.sololearn.com/W367t4UyJ9aF/?ref=app

Answer 2

Your question isn't so clear