/packages/meteor/package.js
it is determined that .css files must be linked.
However, having carefully examined docs.meteor.com , we can find this information:
CSS files work the same way: the client will receive a package with all the CSS in your tree (excluding server and public subdirectories).
This last part is an interesting bit, if you put your CSS files in /public , they will not be combined together. Instead, app/lib/bundler.js runs the following line 517:
files.cp_r(path.join(project_dir, 'public'), path.join(build_path, 'static'), {ignore: ignore_files});
And on the server side, any unresolved files will also be checked in build/static , which means that when you install screen.css in /public you can continue to use screen.css on the client.