Anchor on the background

Hello there, I m creating my first website and I want to put an anchor image in a precise part of the background image. Actually I was able to do that without any problems when the page is in full screen. the problem is when I resize the page: my anchor image is not in the place where it should be :frowning:

Please attach a link to your code (codepen, repl.it, etc). Screenshots are not helpful when trying to debug.