Hi,
You Can use this css for making your site responsive
@media only screen and (max-width: 1400px)and (min-width:770px) {
.vc_gitem-zone.vc_gitem-zone-a.vc-gitem-zone-height-mode-auto.vc-gitem-zone-height-mode-auto-1-1.vc_gitem-is-link
{
height:200px;
background-size:contain;
}
}
output :
http://prntscr.com/qbvf3m