I used all 9 rows for the rainbow so gat I could match the with of the top color to the width of the ribbing.

I added a row of scallops at the bottom and two eyelets for the straps.

Instead of breaking the yarn to make the straps, I slip stitched all around (except the aforementioned scallops and eyelets). Then when I got to the rainbow, I slip stitched the first 20 stitches. Then I chained 150 stitches. Then I slip stitched 150 back to the rainbow. Then I slip stitched the next 14 stitches of the rainbow. Then I chained 150; sl st back to the rainbow 150 stitches, and slip st back to where a started the sl st round.