<div class="container">
  <div class="nav">Navbar</div>
  <div class="main">
    <div class="post">Post</div>
    <div class="post">Post</div>
    <div class="post">Post</div>
    <div class="post">Post</div>
    <div class="post">Post</div>
    <div class="post">Post</div>
  </div>
  <div class="sidebar">
    <div class="section">Section</div>
    <div class="section">Section</div>
    <div class="section">Section</div>
  </div>
  <div class="footer">Footer</div>
</div>
.container {
  display: grid;
  grid-template-columns: auto auto auto;
}

.container div {
  font-family: Georgia, "Times New Roman", Times, serif;
  font-size: x-large;
  text-align: center;
  padding: 20px;
  border: 1px solid orange;
  background-color: bisque;
}

.nav {
  grid-column: 1 / 4;
}

.main {
  grid-column: 1 / 3;
  height: 50vh;

  display: grid;
  grid-template-columns: auto auto auto;
  gap: 10px;
}

.sidebar {
  grid-column: 3 / 4;
  height: 50vh;

  display: grid;
  grid-template-columns: auto;
  gap: 10px;
}

.footer {
  grid-column: 1 / 4;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.