Customizing the site titles per-page using a custom field

gistfile1.php

<?php

function custom_site_title( $html, $location, $logo_tag, $type ) {
	global $post;
	if( is_singular() && $custom_title = get_post_meta( $post->ID, 'site_title', true ) ) {
		$title = get_bloginfo('name');
		$html = str_replace( $title, $custom_title, $html );
	}
	return $html;
}
add_filter( 'themify_site_logo_logo_html', 'custom_site_title', 10, 4 );

/* custom site-description text per-page */
function custom_before_layout( $value ) {
    if( is_singular() && $slogan = get_post_meta( $post->ID, 'Slogan', true ) ) {
		$value = $slogan;
	}

	return $value;
}
if( ! is_admin() )
	add_action( 'option_blogdescription', 'custom_before_layout' );