You may use the following sample maintenance page for your website, when necessary. I did not create it but I did find it very helpful and the link to the HTML code may be found here.
<!doctype html>
<title>Site Maintenance</title>
<style>
body { text-align: center; padding: 150px; }
h1 { font-size: 50px; }
body { font: 20px Helvetica, sans-serif; color: #333; }
article { display: block; text-align: left; width: 650px; margin: 0 auto; }
a { color: #dc8100; text-decoration: none; }
a:hover { color: #333; text-decoration: none; }
</style>
<article>
<h1>We’ll be back soon!</h1>
<div>
<p>Sorry for the inconvenience but we’re performing some maintenance at the moment. If you need to you can always <a href=”mailto:#”>contact us</a>, otherwise we’ll be back online shortly!</p>
<p>— The Team</p>
</div>
</article>