index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Gulp Html Include Boilerplate</title>
    <link rel="stylesheet" type="text/css" href="css/style.css">
  </head>
  <body>
    @@include('./header.html')
    <!-- Content -->
    <section>
      <h1>Hello world</h1>
    </section>
    @@include('./footer.html')
  </body>
</html>