Design an abstract background that conveys the feeling of a city enveloped in fog, using a palette of muted grays, soft whites, and hints of pastel colors. The composition should feature layered, organic shapes that suggest the silhouettes of buildings and trees, partially obscured by a thick mist. The interplay of light and shadow should create a sense of depth, with soft gradients transitioning between colors to mimic the ethereal quality of fog. Incorporate texture overlays to add richness to the background, enhancing the overall atmospheric effect. The result should evoke a sense of calm and mystery, inviting the viewer to explore the hidden details within the fog.