.NAD11935D-stack {
  position: relative;
}
.NAD11935D-stack > div:not(:first-child) {
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
}
.NAD11935D-stack:empty {
  border: 2px dashed #AAAAAA;
  padding: 30px;
  line-height: 1.3em;
  font-family: sans-serif;
  font-size: 14px;
  color: #AAAAAA;
  background-color: #EEEEEE;
  text-align: center;
}
.NAD11935D-stack:empty::after {
  content: "This is an empty stack. Drop first content here, then drop overlayed contents.";
}