Flash of unstyled content (FOUC) in Firefox only? Is FF slow renderer?
If you add a dummy <script> tag right after <body>, Firefox will show the page after all the css from <head> is loaded: <body> <script>0</script> <!– rest of the code –> </body> There is an official bugreport about this FOUC (Flash Of Unstyled Content) on the Firefox site: https://bugzilla.mozilla.org/show_bug.cgi?id=1404468