For elements to overlap, the CSS property position: fixed can be used. If you switch to position: static or remove the position property altogether, the top attribute will no longer have any effect.
Position fixed: This allows you to define the position of an element relative to the browser's borders by setting values for top, right, bottom, and left.
Position absolute: Similar to position fixed, but the top, right, bottom, and left values will be relative to the closest parent element with "position: relative".