code: func (b *Box) Center(container *Box) {
  	widthleftover := container.inner.W - b.frame.W
  	heightleftover := container.inner.H - b.frame.H
  	b.frame.X = container.inner.X + widthleftover/2
  	b.frame.Y = container.inner.Y + heightleftover/2
  }
docs: // Place a Box at the center of the given container.