A lot of you have probably seen browser emulators that allow you to look at your web page in the way that (insert browser in question) renders it. Tools like Browserlab from Adobe and BrowserCam.com are used to test browsers and devices for rendering glitches.
I checked out the response and links for emulating game systems: How do emulators work and how are they written?
I'm interested in specifically, how web browsers render content - where the "rules" for how elements are rendered are defined.
Does anyone know of any resources that discuss this? I'm not looking for tools - I use those already - I want to know how they work.