On MacOSX(10.12) tab bar is overlapped by OSX's menu bar
On MacOSX (10.12.6) in full screen mode the tab bar is overlapped by osx's menu bar, which makes the tab bar unusable.
Setups to reproduce Install Firefox on mac osx go to full screen hover the mouse to top
Application Basics
Name: Firefox Version: 60.0b14 Build ID: 20180419200216 Update Channel: beta User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:60.0) Gecko/20100101 Firefox/60.0 OS: Darwin 16.7.0 Multiprocess Windows: 1/1 (Enabled by default) Web Content Processes: 4/4 Stylo: content = true (enabled by default), chrome = true (enabled by default) Enterprise Policies: Inactive Google Key: Found Mozilla Location Service Key: Found Safe Mode: false