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