Which classic literary series was the first to use a standardized, color-coded spine design as part of its brand identity, creating a distinctive 'rainbow' effect when displayed together on bookshelves?

Throughout publishing history, certain literary brands have created distinctive identities that transcend their books. These visual and marketing elements become instantly recognizable cultural touchpoints. This poll tests your knowledge of the evolution of branding in the literary world and how publishers have crafted unique identities for their most valuable intellectual properties. Can you identify which famous literary brand pioneered a particular branding innovation?

This is a live public trivia poll on AIPolls.Net. Vote and see real-time results.

Penguin Classics (with their black spines and color-coded bands)
Oxford World's Classics (with their gradient-colored spines)
Everyman's Library (with their uniform cloth bindings in different colors)
Modern Library (with their torchbearer logo and varied spine colors)