.leaflet-cluster-anim .leaflet-marker-icon,
.leaflet-cluster-anim .leaflet-marker-shadow {
    -webkit-transition:
        -webkit-transform 0.3s ease-out,
        opacity 0.3s ease-in;
    -moz-transition:
        -moz-transform 0.3s ease-out,
        opacity 0.3s ease-in;
    -o-transition:
        -o-transform 0.3s ease-out,
        opacity 0.3s ease-in;
    transition:
        transform 0.3s ease-out,
        opacity 0.3s ease-in;
}

.leaflet-cluster-spider-leg {
    /* stroke-dashoffset (duration and function) should match with leaflet-marker-icon transform in order to track it exactly */
    -webkit-transition:
        -webkit-stroke-dashoffset 0.3s ease-out,
        -webkit-stroke-opacity 0.3s ease-in;
    -moz-transition:
        -moz-stroke-dashoffset 0.3s ease-out,
        -moz-stroke-opacity 0.3s ease-in;
    -o-transition:
        -o-stroke-dashoffset 0.3s ease-out,
        -o-stroke-opacity 0.3s ease-in;
    transition:
        stroke-dashoffset 0.3s ease-out,
        stroke-opacity 0.3s ease-in;
}