The background legend mentioned with the help of the sup can be ignored by the browser, as "no-repeat" is written twice. Try to write it like this:
background: url ("") non-repeating fixed center;
also check the path you specified in the url. if your images are in a separate folder, you may need to add "../".
PS Although this may not be necessary for your case, it is good practice to mention properties such as background-position (center in the above case). Sometimes, otherwise, the entire property is ignored by the browser. I'm not sure, however, why this is not happening, I'm not sure if this is actually a problem, or it was some other error in my code. Not always, but I ran into this problem 2-3 times.
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