Thank you for your interest.
You can find how to change the style of the selected cell/row here: http://docs.telerik.com/windows-universal/controls/raddatagrid/styling/datagrid-implicitstyling
(SelectionRegionBorder/BackgroundControl and CurrencyControl).
Also, you can override the TelerikGridHeaderBackgroundBrush and TelerikGridHeaderForegroundBrush to change the background and foreground of the DataGridColumnHeader. Here you can find more information about resolving TelerikNamedBrushes : http://docs.telerik.com/windows-universal/common/resolvingteleriknamedresources
where the Dark/Light ResourcePath is the path of the Resource Dictionary files where you have overriden our brushes.
I hope this helps.
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