/* Rinchiuso in un div rende iframe Responsive (Wrap responsive) */
.googlemap_wrap  {
    position: relative;
    padding-bottom: 65.25%;
    padding-top: 30px;
    height: 0;
    overflow: hidden;
}
/* iframe posizionato in maniera assoluta */
.googlemap_wrap iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}