We've been advocating moving our visual implementation (or something similar) to dev tools in both FF and Chrome. Here are some before/after examples to show you how a more abstract input method can really speed up development: http://things-that-web-inspectors-should-have.webflow.io/
Feature request: I understand your goal of visual tooling, but it'd be neat if I could turn on a mode in which the css for a given operation showed up in the tooltip, instead of english descriptions.