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Re: Contrast and Color Accessibility, Understanding WCAG 2 Contrast and Color Requirements

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From: Jared Smith
Date: Dec 4, 2018 10:05PM

Thank you Jonathan and Alistair for your thoughts and resources. The
Github threads were helpful, but seem to have ended without a clear
resolution to this question.

If I understand you both correctly, you are stating that hover state
is not required to have a 3:1 contrast ratio difference from the
default state. This is my understanding as well. Again, it would be
odd to say that no or very subtle change (depending on the browser) on
hover is perfectly fine, but a subtle author-specified color/contrast
change on hover is a WCAG failure that can be remedied only by making
it a rather significant 3:1 contrast ratio change.

I believe this can be better clarified and explained in the
Understanding document for this SC, especially if one infers the
discussion of "states" to apply to more than the visibility of the
focus indicator (which is really covered by 2.4.7 anyway - this SC
just helps to define what "visible" means).

Alistair, there are still some statements you made that muddy the
waters for me...

> There are a remarkable number of states, especially for links [1], so
> differentiating all states from each other is not feasible. The
> intended scope was that the component is perceivable in all it's states

Right, so regardless of the state, the component itself needs to be
perceivable with 3:1 contrast to its surroundings, and there's no
requirement that the individual states themselves have 3:1 contrast
from each other. Gotcha!

> For example, the toggle in a toggle button.

Wait, now I'm confused again! If you mean that in both states (on and
off) that the button itself needs to be perceivable, then I agree.

But if you are instead stating that the two states (on and off) have
to be differentiable *from each other* with a 3:1 contrast ratio
(assuming no other visual or text changes), then this conflicts with
your previous statements. How are the on/off states covered, but the
hover state not covered? The SC doesn't make a differentiation of
types of states.

See how this quickly gets confusing? Authors (and accessibility folks
like me) really need clear guidance on this - the supporting materials
can't say that some states are covered and others not without clear
descriptions of which are which - and explanations of how that aligns
with the normative text.

Thanks,

Jared