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

Design policy: Practicality-first, high-density, efficient. As a B2B office supplies e-commerce site, the top priority is enabling users to quickly browse, search, and order from a vast product catalog - Density: A business e-commerce site with extremely high information density. The body's base font-size is an extremely small 10px, with a layout that packs information into the header, sidebar, and main column - Keywords: Practical, efficient, high-density, trustworthy, business-oriented