I believe it's regular old css. The :has() pseudo class.
// Not actually needed, here
// for competition
.group {}
// Child selector
.group:hover group\/hover\:bg-black {
background-color: black;
}
// Which is essentially the same as
.group:hover child {
background-color: black;
}EDIT: I'm sorry, I mixed you up with the other user who was replying criticising other people's CSS knowledge.
I don't think Tailwind has a built-in `:has` tool, but I suspect it would be easy to add one as a custom class.
the second part of your answer answered it perfectly. Thanks