<p class="box">
  <img src="http://satyr.io/4000x3000/green?delay=3000&text=IMG with WIDTH/HEIGHT" width="2000" height="1500" alt="Image">
</p>  

<p>
  Starting from Chromium 88, Firefox 87, and Safari Technology Preview 118 you can use CSS property <code>aspect-ration</code> for maintaining image placeholders.
</p>
  
/* Placeholder color: */

.box {
  aspect-ratio: 4/3;
  background: grey;
}

/* Responsive/Fluid image: */

.box img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Etc. */

body {
  font-family: sans-serif;
}

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