/* ok */
input:not(:placeholder-shown):valid {
  border-color: #4CAF50; 
}

/* not ok */
input:not(:placeholder-shown):invalid {
  color: #E57373;
  border-color: #E57373; 
}

input:not(:placeholder-shown):invalid ~ label {
  color: #E57373; 
}

/* meh */
input:focus:invalid {
  color: currentColor;
  border-color: #FFB74D; 
}

input:focus:invalid ~ label {
  color: currentColor; 
}

/* Am i spam ? */
#amispam {
  display: block;
  width: 0;
  height: 0;
  margin: 0;
  padding: 0;
  line-height: 0;
  font-size: 0;
  border: none;
  -webkit-appearance: none;
  -moz-appearance: none;
  -ms-appearance: none;
  appearance: none; 
}