I haven't really looked at the fastrender project to say how much of a browser it implements itself, but it does depend on at least one servo crate: cssparser (https://github.com/servo/rust-cssparser).

Maybe there is a main servo crate as well out there, and fastrender doesn't depend on that crate, but at least in my mind fastrender depends on some servo browser functionality.

EDIT: fastrender also includes the servo HTML parser: html5ever (https://github.com/servo/html5ever).