Webflow has improved my workflow a lot. But it would improve it double as much if you could sync custom code with the editor and display it. A quick search on StackOverflow precented me with a great Javascript algorithm for reading CSS class values of a stylesheet 1.
You are maybe more focused on designers and no-coders. But I can tell you that to me as a coder Webflow is a great place to start with the front-end. But it would be a must-have tool only if it could properly read CSS values of a stylesheet in to the editor. If you are afraid of intimidating beginners, make it a feature that can be activated under Settings. Add a button for syncing a CSS class with the editor and make a checkbox to show values that are not currently available in the editor.
You do this, and I’m sure the amount of tutorials and reviews on YouTube will double (free marketing).
In this feedback post, I elaborate the feature request a bit better.