

UI redesigns are a marketing feature for paid products because you need to give people a reason to update. (See Microsoft Windows looking different with every new major version).
Mozilla sees Firefox as a paid product (even if it isn’t) and their marketing team decides for a redesign every few actual major releases (not the bogus major releases to get the release number higher fast).
























Heavy tweaking of Firefox UI (fortunately
userChrome.cssanduser.jsare still available, even if hidden in undocumentedabout:configoptions), heavy tweaking of labwc, using a custom labwc theme, tweaked GTK theme.Window resized to get it all in one readable screenshot.