CSS has a pseudo-class, :focus-visible, that matches when an element is focused using keyboard navigation. It also has :focus-within, which matches when the current focused element is the selected element or one of its descendents. However, this applies not only for keyboard navigation but also mouse and tap focus. A pseudo-class that combines the two, :focus-visible-within, would be useful, but does not currently exist. Here’s an article about it: https://larsmagnus.co/blog/focus-visible-within-the-missing-pseudo-class

The code in the meme implements the logic of :focus-visible-within using the new :has() functional pseudo-class, and has a snippet of fallback behavior for slightly older browsers