This reply has been reported for inappropriate content.
When you give any page element a position of absolute, it is removed from the normal flow of the document (it’s not affected by other page elements and other page elements don’t affect it). It gets placed precisely where you put it, and the coordinates are relative to the closest parent above it with relative positioning. In this case, it’s the <div class="box-two"> which has the relative positioning. So the four divs are placed in the top right, top left, etc of that box.