This is how it looks

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

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and

• Remove Cookies

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

Type about:preferences<enter> in the address bar.

• Cookies; Select Privacy. Under History, select

Firefox will Use Custom Settings. Press the button on the right side called Show Cookies. Use the search bar to look for the site. Note; There may be more than one entry. Remove All of them.

• Cache; Select Advanced > Network.

[v57+] Select Privacy. Across from Cached Web Content, Press Clear Now.

If there is still a problem, Start Firefox in Safe Mode https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

A small dialog should appear. Click Start In Safe Mode (not Refresh). Did this help?

While you are in safe mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

Tried everything mentioned still no luck.

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'.

Execute cttune.exe from Win+R, and enable ClearType and follow the onscreen instruction, it may fix the issue.