Create one finished standalone photographic website background image, 16:9 landscape, approximately 2048 by 1152 pixels. Theme: Astral atlas. Scene: A delicate expanding ivory supernova shell like a fine smoke ring floats off-center on charcoal space, with an ember at its heart. Art direction: Cinematic astronomical concept art with physically convincing star light, delicate dust and extraordinary scale. Deep black, icy silver, amber and restrained red. Avoid purple, rainbow nebula wallpaper and oversized glitter. Composition: retain generous low-detail center space suitable for overlaying website copy, adapting subject placement naturally. This is the actual background artwork, not a website mockup. No text, letters, typography, logos, borders, collages, grids or watermarks. Full-bleed, polished, richly detailed at native resolution.