I've been working on a project lately where to get the exact design I want, I needed to add a decent amount of my own CSS. I filled up the 3000 character limit in the theme CSS by the time I had gotten 1/4 the way through my project and then had to shift the design. My feature request below would reduce the issue I faced.
In my particular case, I needed to add my own CSS styling to many 'groups' to get exactly what I wanted. When inspecting and grabbing the CSS class, each group had it's own ...