Getting the back room ready

The back room at my shop was a little grungy looking so I decided to give it a make over with some paint.  I didn't want to teal green from the front of the shop to extend to the back and make it look to dark, so I painted the back room white.  However, there's the line between the teal and white I needed to deal with.  How do I deal with it?  I paint a fun little swirl and call it a day!