Here is the screen shot

I think Google's default font is Arial. Do you think it could be a more general issue with pages that use Arial? For example, my blog has "Arial" as the preferred font, and "Helvetica" second:

https://www.jeffersonscher.com/ttw/

You can check for sandbox security issues when Firefox has a problem to access fonts installed locally.

• https://wiki.mozilla.org/Security/Sandbox

You can set this pref to 2 or 1 on the about:config page to reduce the sandbox security level.

• security.sandbox.content.level = 1
• close and restart Firefox to make the change effective.

If '1' still doesn't have effect then try '0' to disable the sandbox.

If this didn't work then undo/reverse the change and reset the pref via the right-click context menu to the default value.

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• http://kb.mozillazine.org/about:config

See also:

• https://wiki.mozilla.org/Security/Sandbox#Content_Levels