body {
  margin: 15px;
}

input:invalid {
  border-color: red;
}

input:valid {
  border-color: green;
}

select:invalid {
  border-color: red;
}

select:valid {
  border-color: green;
}

textarea:invalid {
  border-color: red;
}

textarea:valid {
  border-color: green;
}