Custom CSS not working

Having styling issues.

In Other Options > Styles, when I enable Custom CSS, I get a terrible 140px left padding, which pushes my gallery way off center, too far.

When you “Show Customization Options” an editable stylesheet appears, which claims that changes will affect the actual file nggallery.css, and override anything else, but this is not the case. They seem to be independent of each other. What’s more, anywhere I add/modify the padding-left, either in the file directly or in this editable screen in WordPress, has no effect.

If I change the 140 to something smaller, it has no effect.
ngg-galleryoverview {
padding-left: 20px;
}

So basically, none of this customization stuff is working. You can see this on my site at:
https://sequentz.com/gallery-2/

Secondly, how can I change the spacing between thumbnails, horizontally and vertically?

Thank you for any help!