Keep the canvas near-white #fff / near-black #101010 and let the data carry the color.
Reserve blue #266df0 for links, selection, and focus rings.
Make primary buttons ink; invert --btn-text per theme so contrast never breaks.
Build UI as typed cells on 1px hairline grids — Attio is a database you can see.
Color status by meaning: green won, red lost, yellow pending, grey lead.