The child is a green Container that wants to
be 30 × 30. Given that the red Container sizes itself to
the size of its child, it is also 30 × 30.
The red color isn’t visible because the green Container
entirely covers the red Container.

Example 8

The red Container sizes itself to its children’s size,
but it takes its own padding into consideration.
So it is also 30 × 30 plus padding.
The red color is visible because of the padding,
and the green Container has the same size as
in the previous example.

Example 9

You might guess that the Container has to be
between 70 and 150 pixels, but you would be wrong.
The ConstrainedBox only imposes additional constraints
from those it receives from its parent.