Why a single rule found nothing, in words: which of its sides matched no
element, and whether that side was described by a type selector or by an
explicit member set (a filter resolved by the caller). Naming a selector for
a side a filter defined would be a false explanation — the selector is not
what ran.
Why a single rule found nothing, in words: which of its sides matched no element, and whether that side was described by a type selector or by an explicit member set (a filter resolved by the caller). Naming a selector for a side a filter defined would be a false explanation — the selector is not what ran.