Green, blue, purple and orange? Okina's 4 colored aura -_- I suck at composition so I thought that the original picture was too barren with okina holding the apple but I was too lazy to draw a decent looking hobo so I just added that in just because I could.
The orange outline around okina is just to separate her outline from the background. I find that overlapping characters with a plain design background is often a bad idea because the details get drowned out especially in pixel art.
The purple parallelograms are the sides of the door portal and the black paralelogtam is the ingress/egress of the door okina uses to go around.
Wacky stuff. Alternatively you could've just made a slightly curved thin black line separating a light blue soft gradient and a grey gradient (your tool supports gradients I hope) and call it a concrete walkaway during the day.