My client used Platform to setup and run a very simple site. On the version she has, "Edit css" is available under Appearance". I have now setup a subdirectory site using multisites and that "Edit css" option is not available when I activate the theme on that site. What do we need to do to have that option? I see your warning against editing the css file.
After seeing the possibilities, I'll look forward to trying Framework and DMS, but we don't need that here. Custom css is the only additional feature we need.