@Joren - Just use a standard cache buster, as you would on any other HTML page. For the most part CSS shouldn't change once you've got the application developed, but this can be a real pain both when developing and when you push a new revision of CSS.
Cache busting is a simple solution, just use a unique name for each revision of the CSS file. I use an MD5 sum of it's content, this way if I'm developing or pushing a change I can be 100% sure that EVERY[ONE/THING] will rx the latest revision.
Here's my GenerateMD5Hash, it recives a string containing the content to be hashed (in this case it would be your CSS) and returns the Hash of the passed buffer.
/// <summary>
/// Generates an MD5 hash for a buffers content
/// </summary>
/// <param name="cBuffer">A buffer containing the string to be Hashed</param>
/// <returns>The MD5 Hash</returns>
internal static string GenerateMD5Hash(string cBuffer)
{
string cHash = "";
MD5 md5 = System.Security.Cryptography.MD5.Create();
byte[] buffer = System.Text.Encoding.ASCII.GetBytes(cBuffer);
byte[] hash = md5.ComputeHash(buffer);
// Convert the slice of bytes to a Hex string
foreach (byte b in hash) { cHash += b.ToString("x2"); }
return cHash;
}
Hope that helps
Andy