.post input.invalid, .post textarea.invalid {background:#E7BA19; color:#fff; }
.post input.valid, .post textarea.valid {background:#07A838; color:#fff; }

.post span {display:inline-block; vertical-align:top; }

.post span.invalid  {background:#c00; color:#E7BA19; font-weight:bold; text-transform:uppercase; font-size:11px;}
.post span.valid  {background:url('http://www.davidemuci.it/jpg/checked.gif') no-repeat; color:#333;}