5 heuristic bugs that made my design-token tool call a bright cream page "dark and moody"

i maintain a small cli called brandmd. it points a headless browser at any url, reads the computed css, and writes a DESIGN.md that AI coding agents (Claude Code, Cursor, Gemini CLI) can read so they build on-brand UI instead of guessing. last week i ran it on cognition.ai's FrontierCode blog post and the output was embarrassing. the page is cream and bright, basically a magazine layout. here is what brandmd said about it: mood: "Dark and moody" #F7F6F5 got named "Light Muted Orange" (it is...