Edit in JSFiddle

<header>
  Header
</header>
<main>
  Main
</main>
<footer>
  Footer
</footer>
body {
  padding: 0;
  margin: 0;
}

main {
  padding: 10px 0;
}

header, footer {
  background: #acacff;
  padding: 10px 0;
}