Mozilla has shipped Firefox 58 Beta and Developer Edition this Wednesday. Check out our Firefox 58 compatibility notes to get prepared for the final version coming January 2018. The good news is those changes are all about the removal of non-standard features, so we don’t expect any significant issues.
We’re rather interested in Firefox 57 aka Firefox Quantum released this Tuesday, that brings the brand-new Stylo CSS engine. Some layout regressions could be observed, so please let us know via Twitter or whatever if you encountered any broken site. We’d like to take as much time for the research as possible.