grid-template-areas

HTML

<body>
    <header>Header</header>
    <main>Main</main>
    <nav>Navigation</nav>
    <aside>Sidebar</aside>
    <footer>Footer</footer>
</body>

CSS

body {
  width: 100vw;
  height: 100vh;
  
  display: grid;
  grid-template-areas:
    "head head head"
    "nav content sidebar"
    "footer footer footer";

  // Sizing
  grid-template-columns: 1fr 4fr 1fr;
  grid-template-rows: 100px 1fr 50px;
}
 

header {
  grid-area: head;
}

nav {
  grid-area: nav;
}

main {
  grid-area: content;
}

aside {
  grid-area: sidebar;
}

footer {
  grid-area: footer;
}

Main