var style = require("style/useable!css!./file.css");
style.use(); // = style.ref();
style.unuse(); // = style.unref();
```
Styles are not added on require, but instead on call to `use`/`ref`. Styles are removed from page if `unuse`/`unref` is called exactly as often as `use`/`ref`.
Note: Behavior is undefined when `unuse`/`unref` is called more often than `use`/`ref`. Don't do that.
By convention the reference-counted API should be bound to `.useable.css` and the simple API to `.css` (similar to other file types, i. e. `.useable.less` and `.less`).