How to decrease padding around Slideshow: Reels, add caption to one reel

Site URL: https://ladybug-leopard-nh2e.squarespace.com/work/tear-sheets

I'd like to add a caption to one of my reels but there's too much padding.  Also would like to decrease spacing between the other reels.

Try adding to Design > Custom CSS

/* gallery padding */
.gallery-slideshow {
    padding: 0 !important;
}