Wow! Thanx, Bite-the-hand-that-feeds-me!
The last coupla days, I noticed all my Firefox pages in Win-10 looked really crappy,
I searched Firefox (they're always updating, as is Win-10) for answers, but to no avail.
I happen to be nowusing Win-10 Version 1803 Build 17133.1
So I tried the Win-Ctrl-Shift-B and suddenly everything cleared up!
Apologies to Firefox, and thanx, TheRegister!