Mozilla announced in April that it was developing a new UI interface for the upcoming FireFox 57, and was named Photon. This is the first time since 2014 that FireFox has made a major adjustment to its interface design, and FireFox 57 will be a landmark release.
The sidebar shown on the right:
Three point menu:
The browser's error page display has also been redesigned:
Mozilla has also released prototypes for Firefox's various internal pages, including traceless browsing, startup windows, blocked pages, and HTTPS error pages:
If all goes well, developers will take the lead in August this year, FireFox 57 related functional development, and ordinary users will be released in November this year after the formal release of FireFox 57.