<div class="resizer"></div>
.resizer {
  width: 100px;
  height: 100px;
  background: white;
  overflow: hidden;
  resize: both;
}

body {
  background: #ccc;
  height: 100vh;
  margin: 0;
  display: grid;
  place-items: center;
}

External CSS

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External JavaScript

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