dynamic square div without height.

by Saksham Malhotra

HTML

<div class="container">
  <div class="dummy"></div>
  <div class="content"></div>
</div>

CSS

.container {
  display: inline-block;
  width: 50%;
  position: relative;
}

.dummy {
  margin-top: 100%;
}

.content {
  border: 1px solid green;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
}