Hi,
To set css which contains borders, you may use WebDateChooser.CssClass.
To set css which contains font, color, backcolor, you may use WebDateChooser.EditStyle.CssClass.
To set css classes to drop-down-calendar, you may use WebDateChooser.CalendarLayout.XxxStyle.CssClass.
If you EnableAppStyling, then you may use/customize values in ig_datechooser.css and ig_calendar.css files used for StyleSetName and Path.