The original cover is known for its yellow, so that was the natural choice for the color of the border.
INSIDE FRONT COVER
Inside front cover: A collection of images from fantastic artist Enrique Alcatena. Marvel should really hire this guy to do a Doctor Strange comic book.
INSIDE BACK COVER
Inside back cover: Inside back cover: A larger image by Enrique Alcatena. Just beautiful.
I always use the original back cover on the customs.