Published by Chris Coyier
More cleverness by Nikita Vasilyev. The blue glow outline that surrounds focusable elements when they are in their :focus state "flies" (you have to see it) to the next focusable element. So when you tab around, it is very clear where the focus has moved to.
I think it's a light enough effect that the cognitive gains are worth the animation. No feedback yet from anyone visually impaired. It would be great to know if this is helpful to them.