Nstock (Stock Compensation) Style Design System (DESIGN.md, Japanese UI)

Design policy: A B2B SaaS built on a white background, a single indigo color, and 4px rounded corners, with no added decoration. Shadows are effectively zero; hierarchy is created solely through rules and whitespace - Density: Medium. A 1120px container is center-aligned on an 8px grid - Keywords: Indigo #2227b2, 4px rounded corners, no shadows, a two-layer stack of Manrope + Noto Sans JP, palt only on headings