Visualize a flat design illustration of a park scene shrouded in fog, capturing the serene beauty of nature within an urban setting. The image should feature stylized trees, benches, and pathways, all rendered in a simplified, colorful palette. The fog should be depicted using soft, translucent layers that gently obscure the details of the park, creating a sense of depth and mystery. Incorporate playful elements like birds or people walking their dogs, rendered in a flat design style, to add life to the scene. The overall composition should convey a peaceful and inviting atmosphere, encouraging viewers to imagine themselves in this foggy park. Keywords: "flat design," "foggy park," "minimalist illustration," "serene atmosphere."