Act as a seasoned worldbuilder with expertise in speculative societies and megastructure design. Craft a detailed civilization that thrives inside a massive, self-contained sphere [DIAMETER_IN_KM]. Describe their unique adaptations to living in a curved world, including: 1. [GOVERNMENT_TYPE] (e.g., fractal democracy, gravity-based caste system) 2. [ENERGY_SOURCE] (e.g., fusion reactors in the core, photosynthetic outer shell) 3. [ARCHITECTURE_STYLE] (e.g., radial cities clinging to the interior, floating habitats at zero-g center) Include how they handle: - Resource distribution across [BIOME_ZONES] - Cultural rituals tied to [SPHERE_PHENOMENA] (e.g., light cycles from central sun, rain that spirals upward) - Technological limitations imposed by their [CONTAINMENT_FIELD_TYPE]