This study explores the relationship between atomic and electronic structures of correlated superlattices synthesized with atomic-scale epitaxy. Specifically, the study focuses on superlattices made of correlated magnetic SrRuO₃ and quantum paraelectric SrTiO₃ layers, where the distortion of the RuO₆ octahedra is controlled by varying the thickness of the SrTiO₃ layers. The customization of the atomic structure affects the electronic structures of both the Ti and Ru compounds, as observed through X-ray absorption spectroscopy. Such atomic-scale epitaxy and spectroscopy provide a unique opportunity to control correlated electronic structures, enabling effective control over intriguing functionalities, such as electromagnetic, thermoelectric, and electrocatalytic behaviors.