"Design a whimsical and playful illustration of a small boy and his train. The boy has short, messy brown hair, big curious eyes, and a cheerful smile. He wears a red-and-white striped shirt under denim overalls, with small sneakers on his feet. He is sitting on a soft rug in a cozy room filled with scattered toys, focusing intently on a colorful toy train running on a circular wooden track. The train has a bright red engine with a yellow roof and blue and green cars attached. The background features a warm, homey setting with soft lighting, bookshelves, and playful decorations. The art style should be child-friendly and vibrant, with saturated colors and textured, hand-drawn details to evoke a whimsical and joyful atmosphere."