Help with CSS

First of all excuse me if this is not for here, but I don't know where to put my request. It's not specifically about windows.
So .. until now, for years, I was using the extension stylish, for customizing my facebook, on my computer, so that I always had sunny picture on the background. However stylish broke some time ago (I was able to still used it cuz I had the extension installed). I reinstalled my PC now and I can't find a way to put that same sunny picture in the background of the desktop version of facebook. I've tried stylus extension, but none of the themes there gives me the option to upload my custom picture .. I asked GPT and google AI and they gave me a couple of CSS codes to put in the stylus in a new style, but none of them worked. The picture in question is this - I want this with none of the UI elements of facebook touched. Just like it was until recently. Thank you in advance.

Facebook like many websites use a CSP (Content-Security-Policy) that notifies the browser which sources are allowed for loading different element types in a browser including one directive for styles (CSS) and another for images img-src. If a file attempts to load from a non-allowed source the browser should block it. This may be be different for a client side extension.

Most browers you can hit ctrl+shift+i or ctrl+shift+f10 to bring up dev tools, look for a console tab then reload the page. Look for content-security-policy violations and see if one matches your image or style source.

The other most likely reason is Facebook changed their content in such a way the extension no longer knows what element to set

neemobeer said:

Facebook like many websites use a CSP (Content-Security-Policy) that notifies the browser which sources are allowed for loading different element types in a browser including one directive for styles (CSS) and another for images img-src. If a file attempts to load from a non-allowed source the browser should block it. This may be be different for a client side extension.

Most browers you can hit ctrl+shift+i or ctrl+shift+f10 to bring up dev tools, look for a console tab then reload the page. Look for content-security-policy violations and see if one matches your image or style source.

The other most likely reason is Facebook changed their content in such a way the extension no longer knows what element to set

Click to expand...

Again until 2 days ago (before I reinstalled my windows, I had it working. It was with stylish, however I had backed up the file from the theme itself and it worked. But now the backup is gone. However because it was working, that means there is still a way for this.