label.valid {
    width: 24px;
    height: 24px;
    background: url(assets/img/valid.png) center center no-repeat;
    display: inline-block;
    text-indent: -9999px;
}
label.error {
    height: 24px;
    font-weight: bold;
    color: red;
    padding: 2px 8px;
    margin-top: 2px;
}