Focus Appearance
When the keyboard focus indicator is visible, an area of the focus indicator meets size and contrast minimums: at least 2 CSS pixels thick, 3:1 contrast against the unfocused state.
What it requires
WCAG 2.2 SC 2.4.13 (AAA) raises the focus-indicator quality bar above 2.4.7 (AA, "is visible"). The AAA version specifies a measurable thickness (2px) and a measurable contrast (3:1 against the unfocused color).
Most browser-default outlines pass. Designer-customized focus rings often regress — a 1px outline in a low-contrast brand color is the common failure.
Common Shopify failure
Theme that overrides the browser focus ring with `outline: 1px solid #ddd` — too thin and too low contrast.
How to fix it
AccessComply's focus agent injects a `:focus-visible` rule with 2px outline + 2px offset in a contrast-tested color.
Primary source: W3C — WCAG 2.2 Understanding 2.4.13