Change the colors of round 1, 2, 4, 6, 8 to magenta color.
And round 3, 5, 7, 9 with white color.
I added one more row of white to get a length I want.
Finally, I added single crochet (sc) stitches round at the edge with magenta color to give a perfect finish to the hat.
Attach the white ribbon bow knot.