.invalid{
    box-shadow: 0 0 1px red;
}

.contact-form>div{
    position: relative;
}

.contact-form>div::after{
    position: absolute;
    content: var(--my-value);
    font-size: 80%;
    bottom: 0;
    left: 18px;
    z-index: 2;
    color: red;
}

.contact-form>div:last-of-type::after{
    bottom: 8px;
}