使用C＃动态生成CSS文件

I have a site that gets deployed to over a dozen clients. The main website has a base template, and each client has a client folder that overrides the colours. The problem is that there are a lot of CSS files, so making a change that forces us to update every client takes a long time. The automated build process takes care of replacing the updated files.I have a site that gets deployed to over a doze