#testo{text-align:left;font:16px Verdana;height:200px;}
#riga img {border:1px solid #b7b7b7;}
#riga img.ancora:hover {border:1px solid #333;}

/* Gli elementi della riga */
.sx {width: 70%; float:right; box-sizing: border-box;}
.ct {width: 2%;  float:right; padding:20px 3px 0 0; box-sizing: border-box;}
.dx {width: 28%; float:right; box-sizing: border-box;}

@media only screen and (max-width: 750px) {
    #testo {height:auto; border:0px solid grey;}
    #riga img{height:auto;width:100%;}
}

@media only screen and (max-width: 600px) {
    /* For mobile phones: */
    .sx {width:100%;}
    .ct {width:100%; height:20px;}
    .dx {width:100%;}
}