Understanding 'justify-content' and 'align-items' in Different 'flex-direction' Scenarios

[wondersavant]

https://btholt.github.io/complete-intro-to-web-dev-v3/lessons/css/flex
align-items
"So now we've shown you the justify-content property, let's examine align-items. justify-content worries about horizontal justification and align-items worries about vertical alignment."

When 'flex-direction' is set to its default value 'row'. if it's set to 'column,' these roles are reversed