What triggers it. An authored color such as themeVariables.radar.axisColor resolves to less than 4.5:1 against an opaque page. Transparent output is not measured because its host backdrop is unknown.

How to fix it. Choose a foreground or page color that meets the warning’s minimum ratio. The renderer preserves explicit authored paint, so re-run verify after changing the source rather than expecting an automatic repaint.

Minimal reproducer

This source triggers LOW_CONTRAST — checked at build time against the same engine the editor runs.

---
config:
  themeVariables:
    radar:
      axisColor: "#dddddd"
---
radar-beta
  axis speed, cost, safety
  curve current{4,3,5}
  max 5

Open this reproducer in the editor

Run am verify diagram.mmd --json, inspect this code, and apply the smallest source or typed mutation that clears it. If it persists after two mechanical attempts, return the warning and ask for human review.

In the cloned repo, am is bun run bin/am.ts.

Machine-readable: this page as Markdown.

Back to all warning codes, or open a blank editor to try a fix.