Make keyboard focus impossible to miss
G223 describes a focus indicator built to a higher standard than merely visible. Its test has three checks and all three are required. The indicator is visible and not obscured by other content. Its area is at least double the size of a 1 CSS pixel border around the component. And the contrast changes by 4.5:1 or more between the focused and unfocused states, which is a comparison of two states rather than a measurement against a background. Now the part to be clear about. W3C references G223 from no success criterion at all, and it does not appear in the technique list for focus visibility, for focus appearance, or in WCAG's conformance section. The technique describes itself as very similar to another one with a stronger indicator, and that self-description is the only thing tying it to any rule. So treat it as a design standard worth adopting rather than as a conformance route.
How we find it in an audit
Our reviewers photograph the focused and unfocused state of each control, then measure the change between them and the thickness of the ring. A hairline dotted outline in mid-grey is the classic near-miss. Present on inspection, invisible in use. We test against every surface a control appears on, because a ring that works on white often disappears on a colored panel.
How affected users experience it
For a sighted keyboard user the focus ring is the cursor, and a faint one means guessing where Enter will land. People with low vision lose a thin indicator entirely against a mid-tone background. Someone with a motor disability, who cannot easily grab a mouse to reorient, pays the highest price for a weak one. A dark ring inside a light halo survives every surface, which is why the two-color pattern keeps winning.
Passes vs. fails
Passes
:focus-visible { outline: 3px solid #0a3d91; outline-offset: 2px; box-shadow: 0 0 0 6px #ffffff; } gives a dark ring with a light halo, unmistakable anywhere.Fails
a:focus { outline: 1px dotted #999; } is a hairline whisper that vanishes against most of the site's surfaces.This guide is our interpretation of W3C technique G223: Using an author-supplied, highly visible focus indicator. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.