templates/newsletter.php
<body class="single " >
<style>
body {
width: 100%;
height: 100%;
background-color: #333333;
display: flex;
align-items: center;
justify-content: center;
}
#info {
width: 90%;
height: 90%;
background-color: #EEE;
padding: 1em;
}
</style>
<div id="info">
<h1 id="newsletter-title" class="entry-title"><?php echo get_option( 'newsletter_title' ); ?></h1>
<div id="newsletter-content" class="entry-content content">
<?php echo get_option( 'newsletter_content' ); ?>
</div>
</div>
</body>