Why is flex-box wrapping wrong?

Question

css

codepen.io/anon/pen/MKLBxv Big
text and small text are supposed to wrap to the next line, but they don't. With this flex-wrap indicated. Where is the mistake?

Answer 1

Instead of flex-wrap for #first, add flex-flow: column wrap;
codepen.io/anon/pen/vLbzgY
And this is completely useless there:

#wrap {
  flex-wrap: wrap;
}