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Gets or sets the Color object assigned directly to this border.
Use this property to read the border color set by this property, or to apply a fixed color to the border. If the border uses a theme color, use ThemeColor to read or set the theme-based color instead.
Color Color { get; set; }
Property Color As Color
IRange range = worksheet.Range["B2:D4"];
IBorder border = range.Borders[BordersIndex.EdgeBottom];
border.LineStyle = BorderLineStyle.Thick;
border.Color = Color.Red;
Color color = border.Color;