Dopo aver avuto conferma che la mia modifica è stata accettata, posto il nuovo css che prevede la formattazione anche del tag <h3> Saluti Tino PS: non l'ho testato con il validator, spero che vada bene :)
body { padding-right: 50px; padding-left: 50px; font-size: 10px; padding-bottom: 50px; padding-top: 50px; margin: 0px; color: #333333; line-height: 16px; font-family: verdana, sans-serif; background-color: #c0c0c0; } td { font-size: 10px; line-height: 16px; text-align: justify; } h1 { font-size: 32px; font-weight: bold; font-family: monospace; text-align: center; letter-spacing: 40px; background-color: #c0c0c0; color: #808080; text-shadow: 3px 3px 5px black; text-decoration: overline; } h2 { font-size: 24px; font-weight: bold; font-family: monospace; line-height: 16px; text-align: center; background-color: #c0c0c0; color: #808080; } h3 { font-size: 20px; font-weight: bold; font-family: monospace; line-height: 16px; text-align: center; background-color: #c0c0c0; color: #808080; } a { font-size: 11px; background-color: #c0c0c0; color: #666; line-height: 19px; font-family: verdana, sans-serif; text-decoration: underline } a:link { background-color: #c0c0c0; color: #808080; text-decoration: underline } a:visited { background-color: #c0c0c0; color: #808080; text-decoration: underline } a:active { background-color: #c0c0c0; color: #808080; text-decoration: underline } a:hover { background-color: #c0c0c0; color: #000066; text-decoration: none; } img { background: none; border: 0px; margin-left: 20px; margin-right:20px; margin-top:20px; } p { font-size: 10px; line-height: 16px; text-align: justify; }