No dai... rinuncio al W3C.
Peccato, se non fosse per il form, avrei la pagina validata.
Però questa non riesco proprio a comprenderla:

codice HTML:
<textarea tabindex="5" cols="50" rows="10" name="messaggio" id="messaggio" placeholder="Inserisci un testo" required/></textarea>

Line 82, Column 135: end tag for element "textarea" which is not open…essaggio" id="messaggio" placeholder="Inserisci un testo" required/></textarea>✉
The Validator found an end tag for the above element, but that element is not currently open. This is often caused by a leftover end tag from an element that was removed during editing, or by an implicitly closed element (if you have an error related to an element being used where it is not allowed, this is almost certainly the case). In the latter case this error will disappear as soon as you fix the original problem.If this error occurred in a script section of your document, you should probably read this FAQ entry.