Professional Book Cover Generator

Professional book cover prompt for Gemini Nano Banana 2. Unlike generic cover prompts, this one is built around the real visual conventions each genre's readers expect, from romance to thriller to sci-fi. Locked to standard 6x9 book proportions, with placeholder title and author text. 5 variables: genre, concept, art style, title, palette. Perfect for self-published and indie authors. Vertical 2:3, 4K, thumbnail-tested, print-ready.