Suggesting stretch to flex items with `: stretch`

Before sizing flex items is done, the flex container gets to make a suggestion

The flex container can suggest to flex items that they should stretch themselves or align themselves in a particular way in their flex line along the cross axis.

This happens after the flex items have gone through an initial round of sizing.

And after the flex lines have potentially stretched if the flex container is multi-line.

The property is used differently in different layout types.

normal could mean something else in another layout type.

In Flexbox, normal means stretch.

Flex items always have a final say.

Whether or not a particular flex item will “listen” depends on its value of align-self.

So each flex item looks at its value of align-self first.

By default, the value is auto, which means “I’ll size or position myself according to the value of the flex container’s property”.

So if you have a multi-line flex container (that is, is not nowrap), then flex items will stretch themselves in their flex line along the cross axis.