All the menu text colors on all sites suddenly changed from black to all sorts of random colors. On Amazon, for instance, the menu text changed to a shadowed blue which is impossible to read: see attached image. Similarly, duckduckgo changed to a rainbow of colors and no amount of customization on its settings changes the colors back to black. In order to make the Amazon menus legible I had go to color setting on Firefox and change them to always use the system settings. This eliminated the shadowing, but the text remains blue, even though I changed everything to black. Changing themes to dark or installing new themes changes Firefox but makes no difference to any site like Amazon. I did try running the browser in safe mode and it changed the menu text color back to black, but returning to normal mode produces the same errors. Not even restoring my PC to an earlier saved session made any difference. What is going on??