What color horse does the Phantom ride?

In the novel by Gaston Leroux, the Phantom rides a horse called Cesar, "the white horse in the Profeta." This horse is stolen from a stable of twelve horses near the beginning of the story; the groomsmen responsible for caring for the horses note that they have seen the "black shadow" riding a horse they are sure is their stolen Cesar during the night. However, they feel they cannot blame "the ghost" for having stolen the horse and be believed.
Later, Christine relates the story of how she was lifted by the "dark shape" and placed upon this white horse, which she recognizes as definitely being the stolen Cesar. In the recent film adaptation of the story, the horse the phantom rides was depicted as black, but in the book there is an emphasis on the contrast between the dark, cloaked figure and the white horse which is more visible in the night.