input.error { border: 1px solid red; }
label.error {
    background: url('unchecked.gif') no-repeat;
    padding-left: 16px;
    margin-left: .3em;
    min-height: 20px;
    margin-top: 5px;
    display: inline-block;
}
label.valid {
    background: url('checked.gif') no-repeat;
    display: block;
    width: 16px;
    height: 16px;
}