JSFiddle - React, Tailwind, and code Playground

HTML

<div class="full-size" style="background-color:lightgrey">
  <img class="full-size" src="//via.placeholder.com/256x192/008000/ffffff?text=ResizeMe!" style="object-fit: contain">
</div>

CSS

html, body {
  width: 100%;
  height: 100%;
  margin: 0;
  overflow: hidden;
}

.full-size {
  width: 100%;
  height: 100%;
}