Questo è l’errore durante la validazione della pagina (w3c):
The itemprop attribute was specified, but the element is not a property of any item

<!-- #mob-menu -->
    
    <header id="masthead" class="site-header" role="banner"><div class="container">		    <div class="site-branding">
		<a href="https://www./" class="custom-logo-link" rel="home" itemprop="url"><img width="451" height="183" src="https://www.it/wp-content/uploads/2017/07/logo.png" class="custom-logo" alt="Logo" itemprop="logo" srcset="https://www.it/wp-content/uploads/2017/07/logo.png 451w, https://www.it/wp-content/uploads/2017/07/logo.png 300w" sizes="(max-width: 451px) 100vw, 451px" /></a>
						
    </div><!-- .site-branding -->