Thank you for submiting your concerns. We apologize for the delayed answer.
Telerik RadControls use a theming mechanism to employ a certain look. There is also a default theme for all RadControls, which is Office Black. Therefore applying your custom styles will most probably work partially for you as parts of Office Black will still be visible.
While we have themed styles for non-Telerik controls, such as ListBox, TextBox, ScrollViewer, etc, we also have themes for all RadControls that your styles will most probably not be compatible with due to the fact that RadControls have custom templates, use control chromes, additional properties,etc.
I suggest you pick one of the Telerik themes for RadControls for Silverlight (Office Black, Office Blue, Office Silver, Summer, Vista, Windows7, Transparent, Expression Dark) that is closest to the result you wish to acomplish and customize that theme according to your current design.
If you need further help, please let me know.
the Telerik team
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