In a html document the <style> tag seems to be included in the scope of source.css.embedded.html whereas surely it isn't css at all, only the contents between the tag are css.
It's a known issue with the HTML grammar; I've been trying to work out in my head how to rearrange the HTML grammars to be less numerous etc. Once the best approach is figured out they just need to be re- written. In other words it could be fixed, but probably best to put the effort toward a new grammar.
There is a grammar that I made as a proof of concept in the repository Experimental HTML; but it's highly strict, and only supports XHTML 1.0 Strict. On the flipside if your using that it works pretty well. :)