Intrinsic Image Placholders

index.html

<div class="Intrinsic-wrapper">
  <img class="Intrinsic-item Intrinsic-item--1x1" src="">
</div>

<style>
.Intrinsic-wrapper {
  display: block;
  padding-top: 100%;
  position: relative;
  width: 100%;
  height: 0;
}
  
.Intrinsic-wrapper--1x1 {
  padding-top: 100%
}

.Intrinsic-wrapper--2x3 {
  padding-top: 66.66666667%
}

.Intrinsic-wrapper--3x2 {
  padding-top: 150%
}

.Intrinsic-wrapper--4x3 {
  padding-top: 75%
}

.Intrinsic-wrapper--5x4 {
  padding-top: 125%
}

.Intrinsic-item {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}
</style>