[jzelinskie]

So, this might be a case of me assuming too much, but I basically read every instance of _cosmetic filters_ basically as _css styles_. There are a couple CSS files in the git repository that have "filter" in their names[0], but yeah I can't actually be 100% certain at a glance that they're using CSS and not manipulating the DOM with JS.

[0]: https://github.com/gorhill/uBlock/tree/master/src/css

[heycam]

I just did some poking around, and it looks like uBlock does insert a couple of <style> elements into the document. I'm not sure if this is how all style-based blocking is done in uBlock, but since these are document-level style sheets, they are not shared like user agent-level sheets are. (We will in the future be investigating whether we can share more data between common document-level style sheets across multiple documents, though.)