Untitled

<!DOCTYPE html>
<html>
<head>
  <title>Elk Web Design</title>
<style id="jsbin-css">
body {
  margin: 0;
  min-height: 100vh;
}

header {
  height: 100px;
  background: grey;
}

div {
  margin: 0 auto;
  width: 400px;
}

main,
aside {
  float: left;
  display: block;
  min-height: 500px;
}

main {
  width: 200px;
  background-color: red;
}

aside {
  width: 100px;
  background-color: green;
}

footer {
  clear: both;
  height: 100px;
  background-color: grey;
}
</style>
</head>
<body>
  <header>

  </header>
  <div>
    <aside>

    </aside>
    <main>

    </main>
    <aside>

    </aside>
  </div>


  <footer>

  </footer>


<script id="jsbin-source-css" type="text/css">body {
  margin: 0;
  min-height: 100vh;
}

header {
  height: 100px;
  background: grey;
}

div {
  margin: 0 auto;
  width: 400px;
}

main,
aside {
  float: left;
  display: block;
  min-height: 500px;
}

main {
  width: 200px;
  background-color: red;
}

aside {
  width: 100px;
  background-color: green;
}

footer {
  clear: both;
  height: 100px;
  background-color: grey;
}</script>
</body>
</html>