In a previous version of Firefox (v.43.0.2) installed in Linux I was able to use the Helvetica font for the menu toolbar. I did this by specifying options in the userChrome.css file, which was in the chrome directory under my profile directory. Also, when I searched the available fonts in edit -> preferences, the helvetica font was listed. I recently upgraded my Linux OS and installed Firefox v.49.0. I cannot get Firefox-49.0 to use the helvetica font for the menu items, even though I have the same userChrome.css file under the new profile. Also, when I do a search of available fonts with Firefox-49.0, helvetica does not appear in the list. I know that the helvetica font is available in the system -- for example I can find it with the "fc-match -v helvetica" command. But for some reason Firefox doesn't recognize it. My helvetica font is one of the standard Xorg fonts, located in the /usr/share/fonts/X11/75dpi directory. I am far from an expert in fonts, but I believe it is not a scalable font. Is there some reason that Firefox is now ignoring unscalable fonts? Or is it just ignoring the Helvetica font in particular? I know many people have complained about the "Helvetica Neue" font, but I don't think it is the same as the helvetica font I am trying to use. Is it possible that any font with the name "helvetica" has been "blacklisted" due to all the problems with "Helvetica Neue"? Any idea how to coax Firefox-49.0 to use the helvetica font?