.graph {
    width: 464px;
    height: 350px;
    margin: 0 auto 10px;
}
.graph-small {
    width: 304px;
    height: 350px;
    margin: 0 auto 10px;
}
.graph-large {
    width: 624px; 
    height: 400px; 
    margin: 0 auto 10px;
}
.highcharts-tooltip span,
.highcharts-tooltip b {
    color: #fff !important;
}