Google's announcement [1] about OT font variations mentions that a CSS proposal is in the works:
> Together with other browser makers, we’re already working on a proposal to extend CSS fonts with variations. Once everyone agrees on the format, we’ll support it in Google Chrome.
> Together with other browser makers, we’re already working on a proposal to extend CSS fonts with variations. Once everyone agrees on the format, we’ll support it in Google Chrome.
[1] http://opensource.googleblog.com/2016/09/introducing-opentyp...