Custom CSS for Padding on Gallery Sides (Brine)

Does anyone know the name of the (index) gallery container to which I can change the padding in Custom CSS? To replace the .xxx below

.xxx {padding-left, padding-right: 40px;}

I have a site padding of 40px and a padding between index gallery images of 20px.So the gallery sticks out by 20px more than the header and the rest of the site content.(If I put down no side padding for the index gallery in the style editor, then the gallery will stick out by 40px).

I could also apply the padding to the gallery page, instead of the gallery image container.

Using Brine, but I'm not sure it matters.

I figured it out looking at the page source

.Index-gallery {margin-left: 10px; margin-right: 10px;}

It's case specific, though... kind of odd: "Index" needs to be capitalized.

That's correct. HTML class names are case-sensitive.