Firefox 29 to Get New Look, Improved Browser Synchronization
Found on eWEEK on Thursday, 20 March 2014

The most visible new addition in Firefox 29 Beta is the Australis interface, which is the most significant Firefox user interface change since the Firefox 4 release in March 2011. Mozilla developers have been talking about Australis since at least last June as a new design that will revitalize the browser, making it easier for users to get what they want from the Web.
The overall user interface now provides a more fluid look and feel and includes a rounded tab design. Tabs have also been improved to make it easier for users to clearly identify which tab they are on inside the browser.
Firefox isn't improving, it's just copying other browsers.