Note for the readers: this question is not about standard CSS, but it's related exclusively to the CSS support of Codename One.
I'm not satisfied of the Material Font Icons included in Codename One. I want to replace almost all these lines:
FontImage.createMaterial(FontImage.MATERIAL_XXX, "ColorWhite", 4)
with something different taken from Fontello. In the past I read how to do that using the CSS support included in Codename One, but at the moment I'm not finding what I read. I only found this: https://www.codenameone.com/blog/using-icon-fonts-such-as-fontello.html, but it doesn't explain how to use the CSS.
So my question is the correct coding to use Fontello icons inside a Codename One app using CSS (is there any tutorial?).