It sounds like you should be using
position: absolute, which respects the containing block you put it in, but removes that box from the flow. I'm assuming here that you're wanting to place this box outside the main div (You would place it inside the main div in the code, but position it outside with styling). Using
position: fixed is generally only relative to the viewport. I don't understand why you would be using
position: absolute on all elements inside your centering div.