Hi kalindiberad,
Thank you for posting here.
For your question, you could refer to the links below.
https://www.c-sharpcorner.com/UploadFile/a0a81e/3/
https://www.c-sharpcorner.com/UploadFile/8dd3df/themes-in-Asp-Net/
Best Regards,
Wendy
MSDN Community Support
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