Clearly you missed my point if you think gaming.youtube is using css variables. I just looked at their source code. THEY ARE NOT. Maybe they are using a preprocessor or a JS CSS processor as a polyfil. But my question was not "When can I start using this with a preprocess" or "When can I start using this with a JS polyfill". I want this functionality NATIVELY. and if you think you can just ignore 11% of your clients you shouldn't work commercially. The reason I ask this question is because OBVIOUSLY we could start using this with polyfills/preprocessors right now, hell we could YEARS AGO with things like SASS, CSS variables using preprocessors/polyfills are nothing new, they have been around for 5+ years. This article is NOT about preprocessors/polyfills, this article is about NATIVE CSS variables. If you want to have a discussion about preprocessors/polyfills there are other forums for that, but this one is not it.