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

Design policy: A calm corporate design featuring a warm gray #f0f0ee background accented with brand green #82be28. The structure transitions from a full-screen dark hero (black background) at the top to a warm gray content area on scroll. - Density: Body text at 16px with line-height 1.8, a standard and comfortable setting for Japanese typography. Sections are separated by generous whitespace. - Keywords: warm gray, green accent, dark hero, YuGothic, corporate - Characteristics: - YuGothic is the primary font, with fallbacks to Hiragino Kaku Gothic → Lucida Grande → Meiryo. The proprietary typ