<div class="left">
  <p>顶部</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>底部</p>
</div>
<div class="right">
  <p>顶部</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>1</p>
  <p>底部</p>
</div>
* {
  margin: 0;
  padding: 0;
}
.left {
  position: fixed;
  top: 0;
  bottom: 0;
  width: 250px;
  background-color: #c1c1c3;
  overflow-y: auto;
}
.right {
  margin-left: 250px;
  background-color: #f5f5f5;
}

External CSS

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External JavaScript

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