Expanded Hit Areas Must Never Collide
NEVER: Let two interactive elements have overlapping hit areas. This is the failure `interactions-match-hit-targets` creates: expand a sub-24px control with a pseudo-element and adjacent expanded targets overlap invisibly, so paint order decides the hit test and the element painted later steals the clicks. Grow each hit area only to the largest rect that does not collide with its neighbour's; if that lands below 24px, the layout is wrong — widen the pitch between the controls (WCAG 2.2 SC 2.5.8 measures spacing, not just size).
Grow a small control's hit area as large as it will go without overlapping the next control's
/* 20px icons, 4px apart — cap the expansion, do not overshoot into the neighbour */
.icon-btn { position: relative; }
.icon-btn::after { content: ""; position: absolute; inset: -12px -2px; }Bad
Good
Why it matters
This is the rule that makes our own advice safe. "Match Visual & Hit Targets" tells you to expand a sub-24px control with a pseudo-element; "Small Touch Targets" and "No Dead Zones" push the same way. All three are about size, and none of them is about collision. Apply them literally to a row of 20px icon buttons separated by a 4px gap and each 44px pseudo-element overshoots its neighbour by roughly 20px.
Nothing warns you: the pseudo-elements are invisible, the icons still look correctly spaced, and the overlap is resolved silently by paint order — the element painted later wins the hit test. So a click that lands squarely on the star icon can fire the delete button sitting next to it, and the bug only shows up in a support ticket. The fix is a ceiling on the expansion: grow each hit area until it would touch its neighbour's, then stop.
If that leaves you below the minimum, the layout itself is wrong and the controls need a wider pitch — 44px of spacing rather than 44px of overlapping padding. WCAG 2.2 SC 2.5.8 encodes exactly this trade: a target under 24px still passes if a 24px circle centred on it does not intersect the circle of any other target. Spacing, not just size, is what the criterion actually measures.