I made 13 ridges instead of 15, using the yarns from the Green Swirl I unravelled, and worked the sleeves in the same 4x4 ribbing as the body (just like my blue Water Whirl) making sure that 4 purl stitches on the upper sleeves adjoin 4 knit stitches from the circle.
The marvelous broomstick blocking method stretched the cardigan enough to make it comfortable, but it’s still close-fitting - and very light-weight.
Unfortunately, my stupid photo-phone tends to see the beautiful forest green as dark blue or gray.