shadow property
Whether to apply a drop shadow to the graph line. Since 2.3 the
shadow can be an object configuration containing color, offsetX,
offsetY, opacity and width.
Note that in some cases, like stacked columns or other dense layouts, the
series may cast shadows on each other. In that case, the
chart.seriesGroupShadow allows applying a common drop shadow to the
whole series group.
API Docs: https://api.highcharts.com/highcharts/series.apo.shadow
Implementation
Map<String, dynamic>? shadow;