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.

[v56+] Type about:preferences#general<enter> in the address bar. Under fonts and colors, press the Advanced button. Scroll to the bottom, turn on Allow Web Sites To Choose Their Own.

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

Firefox 52+ has changed from Cairo to Skia for canvas/content rendering. When Direct2D on Windows isn't used, Skia is used for content rendering

Would you please try this : Type in the address bar about:config (press Enter) (promise to be careful if asked)

Type in the search bar gfx.canvas and look for the preference: gfx.canvas.azure.backends and set its value to direct2d1.1,cairo,skia

Type in the search bar gfx.content and look for the preference: gfx.content.azure.backends and set its value to direct2d1.1,cairo,skia

Then close and restart Firefox in order for the change to take effect. If this doesn't make a difference, change the values back to their default by clicking 'Reset'.

no change in my problem - button was already checked for "allow web site to choose their own"

Please provide public link(s) (no password) that we can check out. No Personal Information Please !

You can check for sandbox security related issues.

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

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

• 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