Thunder includes easy image styling options at your finger tips. After inserting, click on an image to edit it. Go to the Advanced settings. Just add one (or more) of the following css classes to the « CSS Class » field to style your image in an instant: image-border, image-shadow, image-hover, image-circle, image-fancy
The default WordPress Galleries have also been optimized to look their best when you insert them into any post or page using the « Add Media » button in the editor.