Focus appearance explained

There’s some great stuff coming up in version 2.2 of the Web Content Accessibility Guidelines (WCAG), but there’s one rule that’s particularly difficult to understand: 2.4.13 Focus Appearance.

Update: this rule was simplified considerably when WCAG 2.2 moved to ‘Proposed Recommendation’ on the 20th of July 2023; it was also moved from level AA to AAA. So this article probably isn’t very useful anymore!

What the rule applies to

The rule applies to ‘user interface components’, which means:

• form fields
• links
• buttons

Essentially, any element you typically interact with.

Note: this can also include things like horizontally-scrolling tables.

Indicator style

The focus indicator must:

• be at least 2px thick
• be a solid line
• go round the whole element

Colour contrast

The contrast of the focus indicator is covered already in 1.4.11 Non-text Contrast, so it must provide at least a 3:1 contrast ratio against:

• 3:1 against the background it sits on
• 3:1 against the element (e.g. a button) that has focus

The focus indicator should also be obvious compared to

• how the element looked before it had focus
• other similar elements that aren’t in focus

So Focus Appearance sets the contrast ratio of the focus indicator against the focused element’s unfocused state at at least 3:1.