.adsense {
    width: 970px;
    height: 90px;
    display: block;
}
.adsense:before { display: none !important; }
.adsense ins    { width: 100%; height: 100%; display: block; }
 
@media screen and ( max-width: 1024px ) {
    .adsense        { width: 728px; height: 90px; }
    .adsense:before { content: '1024'; }
}
 
@media screen and ( max-width: 800px ) {
    .adsense        { width: 468px; height: 60px; }
    .adsense:before { content: '800'; }
}

/* etc. */