Advanced Tree Counting: Mathematical Layouts With sibling-index() And sibling-count()
CSS introduces new sibling-index() and sibling-count() functions that allow developers to achieve dynamic element indexing without JavaScript or complex :nth-child rules, enabling cascading animations with a single line of code for any number of elements.
入选理由:sibling-index()返回元素在其父元素中的1基位置索引,sibling-count()返回父元素的子元素总数
