<section id="page">
  <header>Header</header>
  <nav>Navigation</nav>
  <main>Main area</main>
  <footer>Footer</footer>
</section>

#page {
  display: grid;
  width: 100%;
  height: 250px;
  grid-template-areas: "head head"
                       "nav  main"
                       "nav  foot";
  grid-template-rows: 50px 1fr 30px;
  grid-template-columns: 150px 1fr;
}
 
#page > header {
  grid-area: head;
  background-color: #07a787;
}
 
#page > nav {
  grid-area: nav;
  background-color: #ffa400;
}
 
#page > main {
  grid-area: main;
  background-color: #00aefd;
}
 
#page > footer {
  grid-area: foot;
  background-color: #e74c3c;
}