.error.invalid-feedback {
    color: red;
}

.form-control.is-invalid:focus, .form-control.is-invalid {
    border-color: #FF0000;
    box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 8px rgba(255, 0, 0, 0.6);
}