Currently, the WebKit implementation benefits from a style reset, where all CSS values are explicitly reset to "initial" values. It's great when you don't want the document styles affecting your subtree layout. Maybe the spec should do the same.
Also related, bug 15805
This needs to be a separate flag. As it turns out, the native WebKit controls simply hard-code styles. I was wrong.
The question is: do we need a separate flags to control whether document styles apply and whether inheritance works? Maybe one flag is enough?