HTML5 Demo webpage

<!DOCTYPE html>
<html lang="en">

    <head>
        <title>Under Construction</title>
        <meta charset="utf-8" />
        <link rel = "stylesheet" href = "style.css" type = "text/css" />
        <meta name = "viewport" content = "width=device-width, initial-scale = 1.0">
    </head>
    <body class="body">
      <header class = "mainHeader">
            <img width=60% src = "SMART-Piggybacking-Memes-Hero-Banner-3.jpg">
            <nav><ul>
                <li class = "active"><a href = "homepage.html">most view page</a></li>
                <li><a href = "Scene.php">things for people to see</a></li>
                  <li><a href = "Contact.html">tell us stuff</a></li>
                  <li><a href = "Login.php">loggerin</a></li>
                  <li><a href = "Logout.php">bye?</a></li>
                   <li><a href = "ValidateAdmin.php">Autherised Personel only stuff</a></li>
                  </ul></nav>
         </header>
         <div class="mainContent">
             <div class = "content">
                 <article class = "topcontent">
             <header>
                 <h2><a href = "#" rel="bookmark" title="About us"> stuff </a></h2>
             </header>
             <footer>
                 <p class = "post-info">[Insert text here]</p>
                 </footer>
             <content>
                 <p></p>
             </content>
             </div>
             <footer class ="mainFooter">
                 <p>Copyright &copy; 2016</p>
                 </footer>
     </body>
     </html>