My Codepen URL contains a sample code of 3 div blocks being moved to a central block. The moving box have to use "relative" positions. The animation works fine, but when the browser is resized, the boxes aren't inside the central container any longer.   What is the proper way to keep the boxes inside the central container after the browser's window is resized?   Thanks See the Pen REBoZv by weyseal (@weyseal) on CodePen