Claude Code is mostly prose. Reasoning traces, tool output, permission prompts — paragraphs, not tokens. Standard terminal themes treat that prose as filler between syntax elements, so contrast and color decisions are tuned entirely for the wrong content.
Klein-void is four Terminal.app themes built for that reading environment, anchored to Yves Klein's IKB — the ultramarine pigment he registered as a proprietary color in 1960. The blue has unusual perceptual depth on dark backgrounds: it reads as void rather than accent, which is what long prose sessions want.
Pure IKB (the 002FA7 hex value) is perceptually invisible as text on dark — APCA Lc -12. So it lives in ansi:blue as a decorative slot for borders and structural highlights, and a lifted Klein-family value goes in ansi:blueBright for permission-prompt text that has to be legible.
Contrast is measured with APCA Lc rather than WCAG ratios, with per-role gates: body >= 90, subtle >= 75, muted >= 45, accents >= 60. Klein Void Prot (V3) is the only variation where every accent slot clears every gate. The other three make deliberate tradeoffs — V2 accepts Claude's ansi:redBright sand color as a second hero instead of neutralizing it.
One setup requirement that isn't obvious: Claude Code must be set to /theme dark-ansi. Without that, it renders its own hardcoded RGB palette and ignores the terminal's ANSI colors completely.
git clone https://github.com/robertnowell/klein-void
cd klein-void
bash install.sh # installs .terminal profile + fonts to ~/Library/Fonts/
bash restore.sh # full rollback if needed
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