Hardcover book. I was in love with this book as a very young child in the mid-80s (figure around 1986 or1987?)
Took it out from a library/would look at it in school – in Springfield, MA, (just in case location helps).
The book was about a beautiful young girl who was stuck (?) kidnapped (?) Lost (?) in a rainbow. I think she was a princess and each kingdom she ran to/went to as she tried to get home was a different color. I remember loving the illustrations. I want to say it was either watercolor or more detailed hand drawn. Not computer illustrated.
Probably not more than 50 pages.
I remember it being slightly oversized (but I was probably about 7 so take that with a grain of salt). *MIGHT* have been a scholastic book as we had book fairs at school and kids use to buy books from those Scholastic book flyers all the time.
Princess’s name might have started with an A.