Buongiorno.

In un form ho questo:
codice HTML:
<label for="nome">Nome <span>*</span></label><a name="nome"></a>
<input tabindex="1" type="text" name="nome" id="nome" value="" placeholder="Inserisci il tuo nome" required/>
Quando tento la validazione W3C, mi dà questo errore:

Line 74, Column 82: there is no attribute "placeholder"…" name="nome" id="nome" value="" placeholder="Inserisci il tuo nome" required/>✉
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute. If you received this error when using the <embed> element to incorporate flash media in a Web page, see the FAQ item on valid flash.


In pratica non gli piace il "placeholder", ma quello che non capisco è "cosa devo fare?".
Il W3C mi dice che il Placeholder non deve sostituire la Label, ma io la Label ce l'ho.
Forse devo fare qualcosa con il CSS invece che con l'HTML?

Grazie.