Shoes.app :height => 550, :width => 600, :resizable => false do
  background red
  @top = flow :height => 50, :width => 600 do
    background white
  end
  @outer = flow :height => 500, :width => 600 do
    background blue
    @inner = flow :height => 500, :width => 300 do
      background black
    end
  end
end