How to Add a Body Class to the WordPress Activation Page for Targeted CSS Styling

So the activation page (for a multisite network) can be a bit difficult to style for a full-width site that has a background on the body and a background on the #content-sidebar-wrap. Since this section is not part of Genesis (or any theme/framework for that matter) and is part of WordPress (thus no real hooks within the page), you need to add a body class to be able to target style.

[php]
add_action( 'activate_header' , 'wps_add_activate_class' );
/*
* Call body_class filter on activate_header action hook that only appears on wp-activate.php
* @author Travis Smith
*/
function wps_add_activate_class() {
add_filter( 'body_class' , 'wps_activate_class' );
}

/*
* Add specific CSS class by filter
* @author Travis Smith
*/
function wps_activate_class( $classes ) {

// add 'class-name' to the $classes array
$classes[] = 'activation-page';

// return the $classes array
return $classes;
}[/php]