Add custom CSS class to custom post type

Have a look at post_class(). Check if the theme using it (every good theme should). If so then you can use post_class filter to add appropriate classes to the container.

Here is an example how you can use that filter

add_filter('post_class', function($classes){

    if(!is_singular('song'))
        return $classes;

    $additional_classes = array('song-entry', 'masonry-entry', 'col-', 'loop-entry', 'col', 'clr', 'span_1_of_3');

    $classes = $classes + $additional_classes;
    return $classes;

});

Hope it helps. Code not tested