Why change of custom.css in "clean" of Moodle theme is not working?

I'm working with `Moodle Framework`, so I need change layout of `clean` theme, in the [document][1] is written: /style/custom.css This is where all the settings CSS is generated. But why my change in the `custom.css` is not affect in my layout? [1]: https://docs.moodle.org/dev/Clean_theme