The workbench / Colour
Contrast checker.
Find colour pairs that stay readable, with live previews.
Try a starting pair:
Room to read.
A little space, a clear sentence, and a pair of colours that make the words easy to see.
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Solid sRGB colours only. AA targets: 4.5:1 for ordinary text and 3:1 for large text; AAA ordinary text: 7:1. This check covers colour contrast, not every accessibility requirement.