WCAG reference → 1.4.3
1.4.3 Contrast (Minimum) (level AA)
Text needs a contrast ratio of at least 4.5:1 against its background, or 3:1 for large text.
How it shows up in Confluence
Two patterns cause almost all failures. The first is the soft grey people choose for captions and notes, which usually lands near 2.8:1. The second is invisible to the author: a coloured table cell or a custom panel colour behind text that was left at the default, which can easily fall below the threshold without anyone changing the text colour at all.
What to do about it
Darken the text or lighten the background until the pair clears 4.5:1. Large text — 24px, or 18.66px and bold — only needs 3:1, which in Confluence covers H1 headings. Measuring matters here: contrast is not something the eye judges reliably, particularly on a good monitor in a bright room.
What Clearwren checks for this criterion
- Text contrast is below the WCAG AA minimum — Low-contrast text is unreadable for many people with low vision, and for anyone on a dim screen or in sunlight.