Have you ever wondered why you are looking for a solution without providing the problem? It seems like you may be overcomplicating things by wanting to use a templating system when a CSS preprocessor like Sass or Less could do the trick. In fact, Less can work well on both the client and server side. Take a look at
If your heart is set on using an HTML-based templating system to generate CSS, there are some factors to consider. Your CSS templates should be stored alongside your HTML templates, not with your static assets. Additionally, your server needs to correctly serve the generated CSS with the appropriate MIME type, and your HTML must reference the styles using a URL that generates the CSS on each request rather than serving it directly from disk.