Hi, I'm just guessing here, but I suspect there was supposed to be something there, such as an ad or annoying video, and one of your add-ons successfully removed the visible content but failed to remove the background.

If it happened to me, I would right-click the rectangle and click Inspect. This would open the Page Inspector tool and show the HTML code of that area. Sometimes there are very obvious clues in the code about the purpose of that rectangle or its source, and sometimes it's gobbledygook.

(I'm signing off now, it's midnight, so if you don't get a chance to poke around there, perhaps someone else will give it a try.)

Thanks very much. Your diagnostics were correct, but I can't permanently remove the background. I can temporarily remove it by changing both the length and width to 0, but when the page refreshes, all the rubbisg is back.

If you look at the HTML and work your way up the hierarchy, are there any clues to why it is there? If it's not a feature you can turn off, maybe one of your add-ons can be trained to remove it.

It is an advert for some digital currency company. I've decided to live with it. Thanks anyway. :D

Sounds like you might need to find a better adblocker here. Can't say this works but I am using adblocker ultimate and maybe that's way I don't see it.

Thanks very much!!! This did the job.