.leaflet-control-overview {
  margin-right: 10px !important;
  margin-bottom: 10px !important;
  border: 1px solid #bbb;
  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
  }
  
.leaflet-control-overview-map {
  width: 128px;
  height: 128px;
  border: 5px solid white;
  z-index: 1;
  box-shadow: 0 0 8px rgba(0,0,0,0.4);
  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
  }