How to add background/fill color to a bounding_box in Prawn

Is it possible to add a background color to a bounding_box in Prawn?

 bounding_box([100, cursor], width: 80, height: 20) do
    pad_top(7) { text "THIS IS TEXT", size: 8, align: :center }
    stroke_bounds
 end 

Ive tried adding this to the bounding_box block

     background_color: "CCCCCC"

Ive tried adding this inside the block

    fill_color "CCCCCC"
    background_color "CCCCCC"

Nothing seems to work with a bounding_box