Is it possible to change a fieldset's background-color on input:focus?

Question

Is it possible to have the background-color of a form\'s fieldset change when the cursor is inside any of that fieldset\'s text fields?

I assumed this might work, b

Answer 1

This is now possible with :focus-within

The :focus-within CSS pseudo-class represents an element that has received focus or contains an element that has received focus. In other words, it represents an element that is itself matched by the :focus pseudo-class or has a descendant that is matched by :focus. (This includes descendants in shadow trees.)

MDN

fieldset {
  background: green;
  margin: 1em;
}

fieldset:focus-within {
  background: red;
}