<div class="wrapper">
  <div style="background: #EBEBEB;"></div>
  <div style="background: #D9D9D9;"></div>
  <div style="background: #B9B9B9;"></div>  
</div>
body {
  margin: 0;
}

.wrapper div {
    height: 100vh;
    float:left; 
    width:33.33%;
}

External CSS

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External JavaScript

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