<div class="container">
  <div class="aside">
      我是浮动元素
  </div>
    <div class="main">
      我是父元素
    </div>
</div>
.aside {
  width: 100px;
  height: 200px;
  background: red;
  float: left;
}
.container {
  width: 300px;
  background: grey;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.