MarkerCluster.Default.css

.marker-cluster-small {
    /* background-color: rgba(181, 226, 140, 0.6); */
    background-color: rgba(3, 169, 244, .3);
  }
  
  .marker-cluster-small div {
    /*background-color: rgba(110, 204, 57, 0.6);*/
    background-color: rgba(3, 169, 244, .8);
  }
  
  .marker-cluster-medium {
    background-color: rgba(241, 211, 87, 0.6);
  }
  
  .marker-cluster-medium div {
    background-color: rgba(240, 194, 12, 0.6);
  }
  
  .marker-cluster-large {
    background-color: rgba(253, 156, 115, 0.6);
  }
  
  .marker-cluster-large div {
    background-color: rgba(241, 128, 23, 0.6);
  }
  
  /* IE 6-8 fallback colors */
  .leaflet-oldie .marker-cluster-small {
    background-color: rgb(181, 226, 140);
  }
  
  .leaflet-oldie .marker-cluster-small div {
    /*background-color: rgb(110, 204, 57);*/
    background-color: rgba(3, 169, 244, .6);
  }
  
  .leaflet-oldie .marker-cluster-medium {
    background-color: rgb(241, 211, 87);
  }
  
  .leaflet-oldie .marker-cluster-medium div {
    background-color: rgb(240, 194, 12);
  }
  
  .leaflet-oldie .marker-cluster-large {
    background-color: rgb(253, 156, 115);
  }
  
  .leaflet-oldie .marker-cluster-large div {
    background-color: rgb(241, 128, 23);
  }
  
  .marker-cluster {
    background-clip: padding-box;
    border-radius: 20px;
  }
  
  .marker-cluster div {
    width: 30px;
    height: 30px;
    margin-left: 5px;
    margin-top: 5px;
  
    text-align: center;
    border-radius: 15px;
    font: 12px "Microsoft YaHei", Arial;
  }
  
  .marker-cluster span {
    line-height: 30px;
  }