Sangetsu Style Design System (DESIGN.md, Japanese UI)

Design approach: Quiet whitespace and refined organization with a restrained color count. Because this is a field where the interior materials themselves "carry color and pattern," the UI stays strictly achromatic, ceding color to product photography and textures - About Sangetsu: Planning, development, and distribution of wallpaper, flooring, and fabrics. Because it has two flows—BtoB (design firms, construction companies) and BtoC (general consumers)—the header clearly branches between "For Business" and "For General Customers" - Density: Medium to low density. A full-width KV slider, three