add_layout.html

<!DOCTYPE html>
<html>
  
<head>
  <title>finterstellar</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
</head>
  
<body style="background-color:Azure;">

  <header style="background-color:powderblue;">
    <span><a href="index.html">finterstellar</a></span>
    <span>
      <nav>
        <span><a href="#">Venus</a></span>
        <span><a href="#">Earth</a></span>
        <span><a href="#">Mars</a></span>
      </nav>
    </span>
  </header>
  
  <section style="background-color:AntiqueWhite;">
    <article>
      <h1>Earth</h1>
      <p>The Earth is the 3rd planet from the Sun in the Solar system.</p>
      <p>Up to now, the Earth is the only planet that has living creature.</p>
    </article>
  </section>
  
  <footer style="background-color:gray;">
    <p>Footer</p>
  </footer>

</body>
</html>