RWC - the code

/* phone */

@media (max-width: 767px) {

   body .phone { display: block; }

   body span.phone { display: inline; }

   body img.phone { display: inline; }

   body li.phone { display: list-item; height: auto; visibility: visible; }

   body table.phone { display: table; }

   body tr.phone { display: table-row; }

}

 

/* tablet */

@media (min-width: 768px) and (max-width: 1279px) {

   body .tablet { display: block; }

   body span.tablet { display: inline; }

   body img.tablet { display: inline; }

   body li.tablet { display: list-item; height: auto; visibility: visible; }

   body table.tablet { display: table; }

   body tr.tablet { display: table-row; }

}

 

/* desktop */

@media (min-width: 1280px) {

     body .desktop { display: block; }

     body span.desktop { display: inline; }

      body img.desktop { display: inline; }

     body li.desktop { display: list-item; height: auto; visibility: visible; }

     body table.desktop { display: table; }

     body tr.desktop { display: table-row; }

}

 

.phone { display: none; }

.tablet { display: none; }

.desktop { display: none; }

li.phone { display: block; height: 0; visibility: hidden; }

li.tablet { display: block; height: 0; visibility: hidden; }

li.desktop { display: block; height: 0; visibility: hidden; }

 

I will provide updates of this code at www.clickstart.net and www.responsivewebcontent.com.