.area { position: relative; height: 10rem; }
.uno, .due { position: absolute; width: 12rem; height: 6rem; padding: 1rem; border: 1px solid navy; }
.uno { top: 0; left: 0; background-color: #eef4fa; z-index: 1; }
.due { top: 2rem; left: 4rem; background-color: #fff3cd; z-index: 2; }