Can't Get a Different Background Image for a Specific Page

Hello I am using theme Grey White Black. The page in question is https://ilovelightshows.com/community/

I have been trying to change the background color of ONLY that page for a little bit now and can’t figure it out. As you can see I’ve already made it a single column and made it wider using

.page-id-366 .content {width: 1200px;
}

I thought I could use this code to change the background color to black

.page-id-366 .body {background-color: #190707;
}

but it doesn’t seem to work. Any ideas?