The back button in the CSS editor is not working, as reported by Lilly, ondrej, Lilly, and denvergeeks. Lilly provided repro steps and screenshots to demonstrate the issue, which occurs in both desktop and mobile views on Windows Chrome. sam confirmed the issue and stated that it was being investigated. The issue has been fixed, as announced by david, with the solution available in this pull request. Lilly thanked @david for the quick response and fix.