I would also do a 1" (cut the strips 1-1/2" wide) sashing/border in the darkest blue, then a 6" border (cut the strips 6-1/2" wide) for the side border and do an 8" border top and bottom (cut strips 8-1/2" wide) using the medium blue. If that's not wide enough...make the 1" border 2".
Marge