Adding custom CSS field to Media Library image

I was able to add a “tag” field to my Media Library images with the following code:

function wptp_add_tags_to_attachments() {
        register_taxonomy_for_object_type( 'post_tag', 'attachment' );
    }
    add_action( 'init' , 'wptp_add_tags_to_attachments' 

Which I found online and it worked perfectly. This is what it looks like:
See image attachment
I now want to add a field to add a CSS class name to an individual image. But I can’t find nor figure out how to achieve this.
Has anyone done this and can you point me in the right direction on how to accomplish this?
As always… Thanks.