Also happens for me on ubuntu-based distros and fedora too.
Was it working on earlier versions of FF do you know? Probably FF latest versions are buggy since they're trying to re-architect the browser a bit. (electrolysis etc)[DOUBLEPOST=1498291357][/DOUBLEPOST]Update: Yup, probably a FF bug because I tried user-agent-switch addon to set it as Chrome and Edge but it still shows broken webpage. Developer mode tab shows some warning about CSS character encoding not being set properly (blaming the website) but who knows?
Use of getAttributeNode() is deprecated. Use getAttribute() instead. 61tHvuwljLL.js:73:139
Use of getPreventDefault() is deprecated. Use defaultPrevented instead.