JSFiddle - React, Tailwind, and code Playground

HTML

<div class="fixed-ratio-resize">
  <div class="content">
      Resize the fiddle frames to resize this box!
  </div>
</div>

CSS

body,html { height:100%; }

.fixed-ratio-resize {
    /* vertical padding/margin use the WIDTH of the parent box,
       in this case the body width * %
    */
    padding-bottom: 50%;
    width: 90%;
    height: 0;
    border: 1px solid red;
    position: relative;
}
.content {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: yellow;
}