This article is about a subject in the real world.
Information in this article is about real-life people, companies, and objects, and does not relate to the in-universe Sonic series.
Sonic the Hedgehog Modern Style Guide is a style guide book intended for use with the branding and merchandise of the "modern" Sonic the Hedgehog series. The book contains various resources such as character artwork and profiles, packaging mock-ups and design elements.
The book contains about one-hundred and forty pages and it is not publicly available; only given out to companies that make official products for the brand.