<div class="container">
  <div class="left"></div>
  <div class="main"></div>
  <div class="right"></div>
</div>
* {
  margin: 0;
  padding: 0;
}
.container {
  display: table;
  width: 100%;
}

.left,
.main,
.right {
  display: table-cell;
}

.left {
  width: 200px;
  height: 300px;
  background: red;
}

.main {
  background: green;
}

.right {
  width: 100px;
  height: 300px;
  background: blue;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.