Creating a Class or ID for the body tag dependant on browser....

Hi,
Im new to learning C# and .Net platform,
I have been wondering how i would go about:
1. Detecting the browser version
2. Using the browser version and associating a class or id for it
3. Using this class or id to be assigned to the html body tag. 
 
Reason for doing this, as you have probably guessed - Keeping one stylesheet for all browsers but having browser specific styles if any fixes are required.
I know this can be done, i just dont know how.
 
Thank you,
G.
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