Dump this code anywhere in Theme’s template functions.php file (For example, functions.php file for a Theme named “default” would probably reside in the directory wp-content/themes/default/functions.php):
function remove_gallery_style() {
return “<div class=’gallery’>”;
}
add_filter(‘gallery_style’, ‘remove_gallery_style’);
And these are the classes for your stylesheet:
.gallery {}
.gallery-item {}
.gallery-icon {}
.gallery-caption {}