Fix Black On Black Tooltips In Firefox

Can you read it?
When I upgraded my Kubuntu Firefox a while back it started displaying tooltips by the mouse cursor with black text on a slightly less black background making them virtually unreadable. I am currently using Kubuntu 14.04 and Firefox 47.0.
After several months of grumbling, I finally got fed up enough to do some research on how to fix the problem.
With some help from mozillaZine Forums I came up with the following solution.
Put the CSS below into the "chrome/userChrome.css" file in your Firefox profile directory.
tooltip { background-color: Black !important; color: White !important; }
I had to create the "chrome" directory and "userChrome.css" file on my system. My profile directory is "~/.mozilla/firefox/hord02jg.default" in my home directory.
This fix also required the Firefox about:config browser.display.use_system_colors setting set to "false".