Across the latest months, the Mozilla developers introduced (as a concept) Australis, the upcoming default theme for Firefox.
Weeks ago, various Australis pictures emerged on the internets, shortly followed by Australis' availability in the Firefox Nightly UX flavor, Australis implementation applied to Ubuntu's Ambiance and Radiance, too.
The just-mentioned arrival on Ubuntu was materialized as curvy tabs, fancy rounded tabs that transform Firefox into a definitely good-looking web-browser.