<div class="container">
  <p class="column">150px</p>
  <p class="column">1fr</p>
  <p class="column">1fr</p>
  <p class="column">150px</p>    
</div>
.container {
  display: grid;
  grid-template-columns: 150px 1fr 1fr 150px;
  grid-template-rows: auto;
  gap: .5em;
}

@media (max-width: 600px) {
  .container {
    grid-template-columns: 1fr 1fr;    
  }
}

/* ETC (Formatting only): */

body {
  margin: 1.5em;
  font-size: 130%;
  font-family: sans-serif;
  background: #F2F0EC;
  color: #2E2C08;
}

.container {
  border: 10px solid #2E2C08;
  background: white;  
  padding: 1em;
}

.column {
  padding: 0.5em;
  text-align: center;
  background: #e5e3de;
  font-weight: bold;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.