The Author of ‘The King in Yellow’ Could Have Been the King of Horror, by Ted Gioia
http://www.conceptualfiction.com/the_king_in_yellow.html

One of @linda-palapala‘s posts on MAWANG reminded me of reading a Dover Publications edition of this book in my grandfather’s library, I think when I was in high school. I hadn’t thought about this book in at least 20 years. What a blast from the past! “The Repairer of Reputations” is the story I best recall.

Gramps also had Dover reprints of Ambrose Bierce’s The Devil’s Dictionary and Lafcadio Hearn short stories. Along with Arthur Conan Doyle’s complete Sherlock Holmes.

Back when I first read it, I didn’t know that yellow is the color reserved for the emperor in East Asia. It is also the color associated with Earth in the Five Elements/Phases theory of Traditional Chinese Medicine. Annemarie Colbin has a great introduction to the subject in her seminal work, Food and Healing.

Brian Stableford pointed out that the story “The Demoiselle d’Ys” was influenced by the stories of Théophile Gautier, such as “Arria Marcella” (1852); both Gautier and Chambers’ stories feature a love affair enabled by a supernatural time slip.[11] The name Jeanne d’Ys is also a homophone for the word jaundice and continues the symbolism of The King in Yellow.

https://en.wikipedia.org/wiki/The_King_in_Yellow

Apropos of color and the supernatural, green was used to indicate it in such stories as “Sir Gawain and the Green Knight.” (Green [or blue] corresponds to the Wood element. Red = Fire; black = Water; white = Metal or Ether.)