BuddyPress.org

I ran across something similar.

https://wordpress.org/extend/plugins/art-direction/

Allows ‘per blog post’ custom css. Cool.

In the case of bp the css gets queued up on a very selective basis. This is from bp-groups-cssjs.php in /mu-plugins/bp-groups:

function groups_add_structure_css() {

/* Enqueue the structure CSS file to give basic positional formatting for components */

wp_enqueue_style( ‘bp-groups-structure’, site_url( MUPLUGINDIR . ‘/bp-groups/css/structure.css’ ) );

}

add_action( ‘bp_styles’, ‘groups_add_structure_css’ );

We got actions too. Hook ‘bp_styles’ and define an override for the defaults. You might have a problem getting it in the sequence properly.

function my_custom_group_css(){

// check if the file exists and if it does queue it up

‘group-custom-‘ . $bp->groups->slug . ‘.css’

}

add_action(‘bp_styles’, ‘my_custom_group_css’, 99);