<div class="container">
  <div class="main"></div>
  <div class="left"></div>
  <div class="right"></div>
</div>
* {
  margin: 0;
  padding: 0;
}
.container {
  position: relative;
}

.main {
  height: 400px;
  margin: 0 110px;
  background: green;
}

.left {
  position: absolute;
  width: 100px;
  height: 300px;
  left: 0;
  top: 0;
  background: red;
}

.right {
  position: absolute;
  width: 100px;
  height: 300px;
  background: blue;
  right: 0;
  top: 0;
}

External CSS

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External JavaScript

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