Hi @stevetheadi,
You can edit your _brand.php file located in your child theme to this:
<?php
$site_name = get_bloginfo( 'name' );
$site_description = get_bloginfo( 'description' );
$logo = x_make_protocol_relative( x_get_option( 'x_logo' ) );
$site_logo = '<img src="' . $logo . '" alt="' . $site_description . '">';
?>
<a href="<?php echo home_url( '/' ); ?>" class="<?php x_brand_class(); ?>" title="<?php echo
$site_description; ?>">
<?php echo ( $logo == '' ) ? '<h1 class="site-brand">' . $site_name . '</h1>' : $site_logo; ?>
</a>
<h2 class="site-tagline"><?php echo $site_description; ?></h2>
What I did is, I wrapped your site name in h1 tag and added the h2 tag for the site tagline. You probably need the following CSS to adjust the font size and margins:
.site-brand {
margin: 0;
font-size: 150%;
}
.site-tagline {
margin: 0;
font-size: 100%;
}
Hope this helps!