Not true, see here: https://jsfiddle.net/2om8t67a/3/ https://jsfiddle.net/2om8t67a/3/ Images act a bit weird in flex though, so it might be true for img element

Not true, see here: https://jsfiddle.net/2om8t67a/3/ https://jsfiddle.net/2om8t67a/3/ Images act a bit weird in flex though, so it might be true for img elements as direct children of flex containers, but for normal content it's not.