In recent years, we could observe changes in the Firefox interface which made the browser look similar to Google Chrome. The Australis theme with curved tabs and a menu on the right or settings, extensions and a history panel in the main window – those changes made Firefox resemble Chrome. The ghacks.net portal published mockups of the new Firefox interface.
In my opinion, the new GUI makes Mozilla’s web browser look more intuitive and aesthetic.
On screenshot below, we can see that the search bar on the right was removed. Now the tabs do not have curved corners. A new menu appeared on the right of the address bar (icon with three dots).
Navigation icons were updated. Now they look more similar to icons in Chrome.
Probably, with the 57 version which will be released in autumn, the new Firefox will bring a new theme engine. The new engine will bring new features for advanced theme creation, like shapes of interface elements and icon edition.