<main>
  <aside>Banner</aside>
  <div>İçerik</div>
  <div>İçerik</div>
  <nav>Sağ menü</nav>
</main>
main {
  display: grid;
  grid-template-columns: 270px 1fr 2fr min-content;
  grid-gap: 1em;
}

main > * {
  background-color: lightblue;
  font-size: 30px;
  padding: 10px;
}

body {
  font-family: 'Merriweather Sans', sans-serif;
}

External CSS

  1. https://fonts.googleapis.com/css?family=Merriweather+Sans:300,800

External JavaScript

This Pen doesn't use any external JavaScript resources.