All the HTML and CSS shortcode handles are fantastic! I'm able to simply reference my main theme's existing CSS to instantly format the content. What I don't know how to do is formatting the overall list container.
How can reference the main theme's gallery CSS and apply a /div class=mygallerytheme/ wrapper around the list? The div needs to sit just above the starting /ul/. (That div also handles the responsive sizing, formatting, etc.)