form.needs-validation input[type="tel"].is-valid {
  border-color: #198754 !important;
  box-shadow: 0 0 0 0.2rem rgba(25, 135, 84, 0.12);
}

form.needs-validation input[type="tel"].is-invalid {
  border-color: #dc3545 !important;
  box-shadow: 0 0 0 0.2rem rgba(220, 53, 69, 0.12);
}

form.needs-validation .invalid-feedback {
  display: none;
  width: 100%;
  margin-top: 0.25rem;
  color: #dc3545;
  font-size: 0.875em;
  line-height: 1.35;
}

form.needs-validation input[type="tel"].is-invalid + .invalid-feedback {
  display: block;
}