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

Design approach: A wellness e-commerce site built on navy blue, conveying trust and cleanliness. As a brand handling recovery wear and sleep goods, the design balances calmness with a premium feel - Density: Body line-height is a generous 1.8. Product cards and feature sections are laid out with ample whitespace, expressing the composure of a conditioning brand - Keywords: navy blue, clean, wellness, technology × sleep, refined sense of trust - Characteristics: - Two-font system: din-2014 (geometric sans-serif) for headings and UI, Helvetica / neue-haas-grotesk-display (neo-grotesque) for body