<div>
  <div id="parent">
    <div id="child"></div>
  </div>
</div>
* {
  margin: 0;
  padding: 0;
}

#parent {
  border: 10px solid pink;
  overflow: hidden;
}

#child {
  float: left;
  width: 100px;
  height: 100px;
  background-color: skyblue;
}
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