index.php

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">

        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">

    </head>

    <body>

        <header>
            <?php include( "/var/www/html/inc/header.html" ); ?>
        </header>

        <main>

        </main>

        <footer>
            <?php include("/var/www/html/inc/footer.html" ); ?>
        </footer>

    </body>
</html>