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

Design policy: Expresses "trust and practicality" through the contrast of a dark green header against a white background. A straightforward retail UI that minimizes decoration and prioritizes access to product information above all else - Density: A small base size of 12px for body text enables high-density information display. line-height 1.5 is unified throughout, keeping things compact without becoming hard to read - Keywords: dark green, high-density retail, practical, system fonts, flat buttons - Characteristics: - The brand color is dark green #004022–#006b30. The header, nav, and CTAs a