Mozilla is working on several macOS improvements for Firefox
This is the weekly news of Firefox Nightly, Mozilla said that it is working on a number of elements in the macOS version of Firefox to improve its native appearance. The changes described include crushing scroll bars during rubber banding (reaching the bottom and top of web pages), the arrival of native fullscreen, and improvements to improved dark mode handling. The last two items can be enabled in Firefox Nightly for testing purposes.
The current version of Firefox on the Nightly channel is version 90, the version after the major interface overhaul scheduled for June 1. Firefox 90 is expected to launch on July 13, 2021, according to FX Trains which tracks Firefox versions.
According to Mozilla, the new squishy scrollbars are enabled in Firefox Nightly, but native fullscreen and dark mode enhancements need to be enabled. To enable native full screen, go to about: config and light full-screen-api.macos-native-full-screen. To enable enhanced dark mode support, go to about: config again and activate widget.macos.respect-aspect-system.
Work on native fullscreen and enhanced dark mode support is still ongoing, so you should be aware that you may experience issues after enabling these features in Firefox Nightly. As long as Mozilla doesn’t have any major issues, we could see all of these improvements coming with the stable version of Firefox 90.