XEP-0392 contrast checker

Current XEP-0392 colors and contrasts

Demo (no 5.3):

This is a test message on a client using XEP-0392 without §5.3.

Demo user - 13:22

Demo (with 5.3):

This is a test message on a client using XEP-0392 with §5.3.

Demo user - 13:22

WCAG compliance required ratio:

	Relevant Specification	Minimum contrast ratio
Avatar	WCAG 2.1 §1.4.11 Non-Text Contrast (Level AA)	3:1
User name	WCAG 2.1 §1.4.3 Minumum Text Contrast (Level AA)	4.5:1
User name	WCAG 2.1 §1.4.6 Enhanced Text Contrast (Level AAA)	7:1

Alternative suggestion is to pick a lightness value (instead of the background-independent 50 suggested before), such that:

Avatars have a contrast ratio of 4.5:1 to the background. This means that avatars from previous versions that did not use §5.3 adaption are mostly the same color as new version avatars displayed on full white or black. The name preview character should always be in the color that provides highest contrast to the avatar color (black or white).
User names have a contrast ratio of 7:1, so they can be easily read. If contrast ratio of 7:1 is not possible on current background, the color that provides highest contrast to the background is used (black or white).

Demo (alt):

This is a test message on a client using XEP-0392 with alternative lightness calculation

Demo user - 13:22