<div class="container">
  <div class="content">Content…<br/>…<br/>…</div>
  <div class="side-1">Side 1</div>
  <div class="side-2">Side 2</div>  
</div>

.container {
  display: grid;
}

.container > * {
  margin-bottom: .5em;
}

.container > :last-child {
  margin: 0;
}

@media screen and (min-width: 600px) {
  .container {
    grid-template-columns: 1fr 3fr 1fr;
    grid-column-gap: .5em;
  }
  
  .container > * {
    margin-bottom: 0;
  }
  
  .side-1 {
    order: -1;
  }
}

/* etc: */

.container > * {
  padding: 1em;
  background: #b3e888;
}

External CSS

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External JavaScript

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