If you are using Arch Linux: pacman -S otf-fira-sans
Thanks! Helped me solve this in Gentoo: emerge -av fira-sans
Same problem here in Firefox 44. If I disable the CSS rule that sets the font to Fira Sans, the text renders normally; that font seems to not render at all. The "Fonts" view in the console doesn't render the sample text ("Abc") either.
What OS? Firefox Developer Edition doesn't have this issue on Windows (haven't checked Linux).
I'm running Firefox Developer Edition 46.0a2 on Linux and I don't see this problem either.
works fine on ubuntu 14.04
using Firefox Nightly 47.0a1 (2016-02-28)
I can read just fine. The website uses Fira Sans font, maybe there's an issue with that, check your browser's console.