Gray Light Font on web pages

[Ka-Spel]

Hello all,
On majority of web pages I see light gray font (see attached examples). This happened the two days ago and I have no idea how this happened.
Under Content/Advance/Allow pages to choose their own fonts, instead of my selections above was turned off so I switched it on to no effect, pages still show the light font.
Web pages on Chrome look fine it's just FF.
I'm using FF 50.1.0, haven't updated but even if I do i'm sure no change will happen.

I looked at a couple of other threads but the suggestions didn't seem to help.

Any clues ?

Click on images when they open for large view.
https://i.imgur.com/ueufyJP.jpg

Font on Ebay is really thin and somewhat light
https://i.imgur.com/cPhhNKR.jpg
https://i.imgur.com/Dmc3F2R.jpg
https://i.imgur.com/um58bUq.jpg

[DanRaisch]

I'm using FF 50.1.0, haven't updated but even if I do i'm sure no change will happen.

Why?

Have you tried starting Firefox in Mozilla Safe Mode? http://kb.mozillazine.org/Safe_mode
If no improvement using Safe Mode, do you have the same problem if you create a new profile and test it with no extensions or non-default themes installed?
http://kb.mozillazine.org/Profile_Manager
and
http://kb.mozillazine.org/Creating_a_ne ... on_Windows

[dickvl]

Did you check the default colors as set in Options to make sure that you haven't set a rather light text color?
Options -> Content: Fonts & Colors -> Colors

If you use a userContent.css file then check its content.
http://kb.mozillazine.org/userContent.css

[Reflective]

Make a backup of your current profile first while you still have the opportunity to do so. That will allow you to install Firefox ESR which supports legacy extensions until June 26 next year.

Hit Windows key + R to open the Run command and then copy/paste the following text in bold font and then click OK (or just hit Enter): %APPDATA%\Mozilla\Firefox\Profiles Make a copy of your current profile. If there's more than one of them present, you can identify the current one either by the date, or by copy/paste the following into the location bar and hit Enter: about:profiles

Decide whether you want to keep your current extensions which are probably all "legacy". This means that they will stop working when Firefox 57 is released mid-November.

If you want to keep them, download Firefox ESR from here first: https://www.mozilla.org/en-US/firefox/o ... tions/all/

Next, uninstall Firefox 50.0.1 which you're using now, but leave your personal data in place if it prompts you for a response. Then install Firefox ESR which is currently 52.4.0 which might even fix the problem without further troubleshooting.

If you're not bothered about keeping your legacy extensions, just update to Firefox 56x which is the current version.