<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8" />
  <style>
    .container {
      display: grid;
      grid-gap: 5px;
      grid-template: auto / 1fr 3fr 1fr;
      background: lightyellow;
    }

    header, aside, section, footer {
      background: lightblue;
      font-family: sans-serif;
      font-size: 3em;
    }

    header, footer {
      grid-column: span 3;
    }

    main {
      grid-column: span 3;
      display: grid;
      grid: subgrid / subgrid;
    }

    .aside1 {
      grid-column: 1;
    }

    .aside2 {
      grid-column: 3;
    }

    section {
      grid-column: 2;
    }
  </style>
</head>
<body>
  <div class="container">
    <header>Header</header>
    <main>
      <aside class="aside1">aside</aside>
      <section>section</section>
      <aside class="aside2">aside2</aside>
    </main>
    <footer>footer</footer>
  </div>
</body>
</html>
