Customize Cluster Color

This seems to work. 



/* Small Clusters (< 10 markers) / .marker-cluster-small { background-color: rgba(250, 132, 25, 0.6) !important; / Outer ring / } .marker-cluster-small div { background-color: rgba(250, 132, 25, 0.6) !important; / Inner circle */
}

/* Medium Clusters (< 100 markers) */
.marker-cluster-medium {
background-color: rgba(250, 132, 25, 0.6) !important;
}
.marker-cluster-medium div {
background-color: rgba(250, 132, 25, 0.6) !important;
}

/* Large Clusters (≥ 100 markers) */
.marker-cluster-large {
background-color: rgba(250, 132, 25, 0.6) !important;
}
.marker-cluster-large div {
background-color: rgba(250, 132, 25, 0.6) !important;
}

/* Optional: change the cluster text color */
.marker-cluster span {
color: #ffffff;
}