style.css

form p {
    margin-top: .25rem;
    font-size: .875em;
}

.invalidStyle {
    color: #dc3545;
}

.validStyle {
    color: #198754;
  }

input {
    background-repeat: no-repeat;
	background-position: right calc(.375em + .1875rem) center;
	background-size: calc(.75em + .375rem) calc(.75em + .375rem);
}

.inputValid {
	border-color: #198754;
	background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 8 8'%3e%3cpath fill='%23198754' d='M2.3 6.73L.6 4.53c-.4-1.04.46-1.4 1.1-.8l1.1 1.4 3.4-3.8c.6-.63 1.6-.27 1.2.7l-4 4.6c-.43.5-.8.4-1.1.1z'/%3e%3c/svg%3e");
}

.inputInvalid {
    border-color: #dc3545;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 12' width='12' height='12' fill='none' stroke='%23dc3545'%3e%3ccircle cx='6' cy='6' r='4.5'/%3e%3cpath stroke-linejoin='round' d='M5.8 3.6h.4L6 6.5z'/%3e%3ccircle cx='6' cy='8.2' r='.6' fill='%23dc3545' stroke='none'/%3e%3c/svg%3e");
}