Sets the color of a chart's vertical grid marks. The default value is Transparent.
For Polar Charts, this attribute sets the color of the chart's radial grid marks.
Enter a color by name, decimal RGB value, or hex RGB value. Prefix hex values with the pound sign, like #112233.
In the animated scatter plot, the color will only be applied and vertical lines shown when "No. Vertical Lines" attribute is set. The default value for animated scatter plots is grey.