.marker-cluster-small {
  background-color: rgba(255, 175, 175, 0.6);
}
.marker-cluster-small div {
  background-color: rgba(252, 122, 122, 0.6);
}

.marker-cluster-medium {
  background-color: rgba(255, 93, 93, 0.6);
}
.marker-cluster-medium div {
  background-color: rgba(252, 49, 49, 0.6);
}

.marker-cluster-large {
  background-color: rgba(252, 34, 34, 0.6);
}
.marker-cluster-large div {
  background-color: rgba(255, 0, 0, 0.6);
}

.marker-cluster-extra-large {
  background-color: rgba(253, 0, 0, 0.6);
}
.marker-cluster-extra-large div {
  background-color: rgba(146, 0, 0, 0.6);
}
.marker-cluster-extra-large div span {
  color: #fff;
  font-weight: 700;
}