Two-Column (Table-style) Edit Screen Layout?

Ooooh, found it here.

So I kind of get the point, but that made me wonder if anybody’s tried using flexbox on these forms.

This trick of using a rich text component to enter CSS: is that a supported feature? Also I would have expected that component to be above the styled components, so that was a surprise. Finally, are the IDs/classnames used within the form documented anywhere?

Thanks again.