As I'm working through learning Webflow, it's apparent that a best practice for nesting Classes is to start any class definitions at the "top" of the Navigator tree, and move down with overrides/nesting as necessary.
I think there can be a UI improvement to facilitate this practice.
In the Styles pane, near the Selector input, have another "input" that will always make available a tree of the children of the current selector on hover, and disappear after selection or mouseout.
That way, you can systematically style down your Classes tree with a "hover+click" while remaining in the Styles pane rather than a "click+click+click" (click-to-get-to-navigator, click-to-choose, click-to-get-back-to-styles.)
If there is a shortcut I'm missing, please let me know.