gecko-dev/layout/reftests/css-valid/input/style.css

/* Override default style */
input:invalid {
  box-shadow: none;
}

input.notvalid {
  background-color: green;
}
input.notvalid:valid {
  background-color: red;
}

input.valid {
  background-color: red;
}
input.valid:valid {
  background-color: green;
}