.gm-cluster-marker {
    position: absolute;
    text-align: center;
    font: bold 10px sans-serif;
    cursor: pointer;
}

.gm-cluster-chart {
    box-sizing: border-box;
    position: absolute;
    background-color: #09f;
    border-radius: 50%;
    border-style: solid;
    cursor: pointer;

    background-color: #7BB32B;
    color: white;
    border-color: rgba(255, 255, 255, 0.5);

    transition: background-color .2s;
}
.gm-cluster-chart:hover {
    z-index: 100;
}
.gm-cluster-chart:hover .label {
    text-shadow: 0 0 2px white;
}

.gm-cluster-chart .value {
    display: block;
    position: absolute;
    top: 50%; left: 0;
    height: 15px; width: 100%;
    margin-top: -7px;
    text-align: center;
    color: white;
    font-weight: bold;
    font-size: 15px;
    line-height: 1;
}

.gm-cluster-chart .label {
    position: absolute;
    bottom: -30px;
    left: 50%;
    transform: translateX(-50%);
    color: #09f;
    font-weight: bold;
    font-size: 20px;
    line-height: 1;
    height: 20px;

    transition: color .2s, text-shadow .2s;
}