Why doesn't the "justify-self: flex-end;" property work?

Question

Flexbox

Hello! There is such code:
https://jsfiddle.net/cLm6fqeo/
Can you please explain why the button with the class "btn" is not pressed to the bottom of the parent? She has the same justify-self: flex-end;, and the parent flex-direction: column;.

Answer 1

The property justify-selfis specific to the CSS Grid module and does not work when used in Flexbox.

Answer 2

it's done like this