a System.Drawing.Color
Use the Style.BorderColor property to specify the border color of the Web server control. This property is set using a System.Drawing.Color object.
This property will render only for certain controls. For example, System.Web.UI.WebControls.Table, System.Web.UI.WebControls.Panel, System.Web.UI.WebControls.DataGrid, System.Web.UI.WebControls.Calendar, and System.Web.UI.WebControls.ValidationSummary will render this property. It will also work for System.Web.UI.WebControls.CheckBoxList, System.Web.UI.WebControls.RadioButtonList, and System.Web.UI.WebControls.DataList if their RepeatLayout property is RepeatLayout.Table and not RepeatLayout.Flow. However, it is rendered as the bordercolor attribute, which may not work in all browsers.