Some weeks ago, I started having problems with the tooltips on Firefox. I can see them, but they don't have a background, so they're impossible to read. I have tried cleaning the cache/cookies and all of that stuff on Firefox but still can't see them. It works fine for me on IE though. Any ideas ?
Have you tried disabling any addons and making sure you are using the most up to date version of Firefox? The background is just a color, so I'm not sure what would stop that from showing.
Nothing that is easy for you to do. If you know how, you can hover until you see a tooltip, open the dev tools, unhide the tooltip div and try and see what is happening to the background color CSS rule.
Maybe try turning off hardware acceleration? Other than that I am out of ideas.
The background colour is defined as "transparent" in the inspector. However, I'm not sure that's the tooltip background instead of the link background.
Sorry to bother you again, but I don't know how to inspect that element, since if I move the mouse the tooltip disappear. Could you please tell me how to do it?