Would a webserver configuration file count? The code on the webserver minifies the CSS file and embeds it into a Link header - you could configure a webserver to respond with a generated Link header and no content to a certain URL.

Here is an example configuration file for nginx: https://snip.dssr.ch/?7a4e21dde5f7916b#2aPagYEg3kuWg3YN8Q5oz...

Though I would argue that the header-embedded CSS is still code, regardless how it is delivered.

An empty file is technically a webpage, right?

Is 'about:mozilla' close enough for you? (Firefox only obv.)

Easy. Just use the nocode language for that.

https://github.com/kelseyhightower/nocode

base64 encoded url thingy