Highcharts .NET: Highsoft.Web.Mvc.Charts.BarSeriesDataLabels Class ... Styles for the label. The default color setting is"contrast", which is a pseudo color that Highcharts picks upand applies the maximum contrast to the underlying point item,for example the bar in a bar chart.The textOutline is a pseudo property that applies an outline ofthe given width with the given color, which by default is themaximum contrast to the text.