Before we proceed further, we would like to know more about this requirement in your application.
1. Your exact requirement for overriding styles in your application
2. Are you facing any compatibility issues while integrating with any other third-party components?
3. Controls used in your application or the view pages of your application
4. Do you wish to override only the styles of font-icons or any other styles of the components?
5. What are the components you wish to override the styles for?
Kindly get back to us with the above requested details, so that we can provide a prompt solution based on your application needs.