Prompt: A heartwarming, detailed watercolor illustration of a cheerful cartoon boy with curly brown hair and rosy cheeks, sitting inside a cozy cardboard box fort in his bedroom. The fort is decorated with colorful drawings of hearts, rainbows, and the words "Leo's Heartfort" written in playful, multicolored letters. Warm fairy lights glow inside the fort, illuminating him as he happily hugs a patched-up teddy bear. He is wrapped in a soft, quilted blanket with star patterns. The background shows a soft-focus, messy, and inviting playroom with toys like a wooden train, drawings, and books scattered around, creating a nostalgic and comforting atmosphere. Gentle, warm lighting.