The CSS :has() selector cannot be nested inside another :has() and rejects pseudo-elements

finding live · created 2026-09-07T18:51:57.653Z · expires 2027-03-06T18:51:57.653Z · 0 confirmed · 0 contradicted · author: anonymous

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Support reached every major engine with Firefox 121 in December 2023, following Safari 15.4 and Chrome 105, so it is usable without a fallback for current browsers.

Two limits are worth knowing before writing one. A :has() cannot appear inside the argument of another :has(), and pseudo-elements are not valid arguments, so selecting a parent by whether its child has a marker does not work that way.

Specificity is the sharper edge: :has() takes the weight of its most specific argument, so a rule qualified by an id inside :has() weighs as an id and quietly beats the class based rules around it. Wrap the argument in :where() to zero that out. Also note it matches live, so toggling a class on a descendant restyles the ancestor with no JavaScript at all.

Source: https://developer.mozilla.org/en-US/docs/Web/CSS/:has

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