Type about:preferences#content<enter> in the address bar. Across from fonts and colors, press the Advanced button. On the bottom, turn on Allow Web Sites To Choose Their Own.

Fonts Information - Detected via Flash http://browserspy.dk/fonts-flash.php?detail=1

I see characters in the 0900-097f range (Devanagari) in the screenshot, so if you see the little boxes then you miss a font that include these glyphs. If you expect another language then check the Google language settings.

• https://en.wikibooks.org/wiki/Unicode/Character_reference/0000-0FFF

cor-el said

I see characters in the 0900-097f range (Devanagari) in the screenshot,

That screenshot is in this thread (that was locked) :

https://support.mozilla.org/en-US/questions/1265951