I have encountered a weird problem with the recent version of Mozilla Firefox (49.0) on Loki. There seems to be a bug when displaying Wikipedia pages - words in italics are simply left out. See e.g. here:
With Google Chrome 53.0.2785.143
and Chromium 53.0.2785.143
there's no problem at all. I haven't noticed the issue on any other web page except Wikipedia.