Tokyo National Museum (TNM / Tobu) Style Design System (DESIGN.md, Japanese UI)

Design policy: Almost everything is composed with three colors: white background, charcoal black #2b2b2b, and deep green #1b854d. Structure is built solely from rectangular surfaces with no rounded corners whatsoever and 1px rules. Zero shadows - Density: The information volume is high, but readability is achieved through line-height 2.0 and generous whitespace. A design that organizes "UI for research" — collection items, exhibition schedules, and the opening calendar — without decoration - Keywords: charcoal black, deep green, rectangular, palt, line-height 2.0