LeafletMakeCluster.css

.marker-cluster-small {
    background-color: rgba(181, 226, 140, .6)
}

.marker-cluster-small div {
    background-color: rgba(110, 204, 57, .6)
}

.marker-cluster-medium {
    background-color: rgba(241, 211, 87, .6)
}

.marker-cluster-medium div {
    background-color: rgba(240, 194, 12, .6)
}

.marker-cluster-large {
    background-color: rgba(253, 156, 115, .6)
}

.marker-cluster-large div {
    background-color: rgba(241, 128, 23, .6)
}

.leaflet-oldie .marker-cluster-small {
    background-color: #b5e28c
}

.leaflet-oldie .marker-cluster-small div {
    background-color: #6ecc39
}

.leaflet-oldie .marker-cluster-medium {
    background-color: #f1d357
}

.leaflet-oldie .marker-cluster-medium div {
    background-color: #f0c20c
}

.leaflet-oldie .marker-cluster-large {
    background-color: #fd9c73
}

.leaflet-oldie .marker-cluster-large div {
    background-color: #f18017
}

.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 "Helvetica Neue", Arial, Helvetica, sans-serif
}

.marker-cluster span {
    line-height: 30px
}

.leaflet-cluster-anim .leaflet-marker-icon, .leaflet-cluster-anim .leaflet-marker-shadow {
    -webkit-transition: -webkit-transform .3s ease-out, opacity .3s ease-in;
    -moz-transition: -moz-transform .3s ease-out, opacity .3s ease-in;
    -o-transition: -o-transform .3s ease-out, opacity .3s ease-in;
    transition: transform .3s ease-out, opacity .3s ease-in
}

.leaflet-cluster-spider-leg {
    -webkit-transition: -webkit-stroke-dashoffset .3s ease-out, -webkit-stroke-opacity .3s ease-in;
    -moz-transition: -moz-stroke-dashoffset .3s ease-out, -moz-stroke-opacity .3s ease-in;
    -o-transition: -o-stroke-dashoffset .3s ease-out, -o-stroke-opacity .3s ease-in;
    transition: stroke-dashoffset .3s ease-out, stroke-opacity .3s ease-in
}